Mercurial > cpython-lru_cache-weakref
annotate Misc/FAQ @ 5215:f70042c19c57 legacy-trunk
Added two new questions about number conversions.
| author | Guido van Rossum <guido@python.org> |
|---|---|
| date | Tue, 25 Mar 1997 18:25:20 +0000 |
| parents | 5878a5af3148 |
| children | b0d9de3786ec |
| rev | line source |
|---|---|
| 1529 | 1 Subject: FAQ: Python -- an object-oriented language |
|
1579
021daabe69d8
Updated for existence of newsgroup and various misc things
Guido van Rossum <guido@python.org>
parents:
1547
diff
changeset
|
2 Newsgroups: comp.lang.python,comp.answers,news.answers |
|
021daabe69d8
Updated for existence of newsgroup and various misc things
Guido van Rossum <guido@python.org>
parents:
1547
diff
changeset
|
3 Followup-to: comp.lang.python |
|
4221
66913ca7ec47
New email and zip code for Guido
Guido van Rossum <guido@python.org>
parents:
3865
diff
changeset
|
4 From: guido@cnri.reston.va.us (Guido van Rossum) |
|
2716
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
5 Reply-to: guido@cnri.reston.va.us (Guido van Rossum) |
|
4278
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
6 Expires: Sun, 1 Dec 1996 00:00:00 GMT |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
7 Supersedes: <DxJ3t1.CJv@cwi.nl> |
| 1529 | 8 Approved: news-answers-request@MIT.Edu |
| 9 | |
| 10 Archive-name: python-faq/part1 | |
|
4221
66913ca7ec47
New email and zip code for Guido
Guido van Rossum <guido@python.org>
parents:
3865
diff
changeset
|
11 Submitted-by: Guido van Rossum <guido@cnri.reston.va.us> |
|
4278
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
12 Version: $Revision$ |
|
4408
6c771ea38eee
Added item about bug in Slackware96 libdl.
Guido van Rossum <guido@python.org>
parents:
4376
diff
changeset
|
13 Last-modified: $Date$ |
| 1529 | 14 |
| 15 This article contains answers to Frequently Asked Questions about | |
| 16 Python (an object-oriented interpreted programming language -- see | |
| 17 the answer to question 1.1 for a short overview). | |
| 18 | |
|
4278
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
19 Copyright 1993-1996 Guido van Rossum. Unchanged electronic |
| 1529 | 20 redistribution of this FAQ is allowed. Printed redistribution only |
| 21 with permission of the author. No warranties. | |
| 22 | |
| 23 Author's address: | |
|
3207
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
24 Guido van Rossum |
|
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
25 C.N.R.I. |
|
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
26 1895 Preston White Drive |
|
4221
66913ca7ec47
New email and zip code for Guido
Guido van Rossum <guido@python.org>
parents:
3865
diff
changeset
|
27 Reston, VA 20191 |
|
3207
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
28 U.S.A. |
|
4221
66913ca7ec47
New email and zip code for Guido
Guido van Rossum <guido@python.org>
parents:
3865
diff
changeset
|
29 Email: <guido@python.org>, <guido@cnri.reston.va.us> |
| 1529 | 30 |
| 31 The latest version of this FAQ is available by anonymous ftp from | |
|
3727
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
32 <URL:ftp://ftp.python.org/pub/python/doc/FAQ>. It will also be posted |
| 2048 | 33 regularly to the newsgroups comp.answers <URL:news:comp.answers> and |
| 34 comp.lang.python <URL:news:comp.lang.python>. | |
| 1529 | 35 |
| 2048 | 36 Many FAQs, including this one, are available by anonymous ftp |
| 37 <URL:ftp://rtfm.mit.edu/pub/usenet/news.answers/>. The name under | |
| 38 which a FAQ is archived appears in the Archive-name line at the top of | |
| 39 the article. This FAQ is archived as python-faq/part1 | |
| 40 <URL:ftp://rtfm.mit.edu/pub/usenet/news.answers/python-faq/part1>. | |
| 1529 | 41 |
| 42 There's a mail server on that machine which will send you files from | |
| 43 the archive by e-mail if you have no ftp access. You send a e-mail | |
| 2048 | 44 message to <mail-server@rtfm.mit.edu> containing the single word help |
| 45 in the message body to receive instructions. | |
| 1529 | 46 |
| 47 This FAQ is divided in the following chapters: | |
| 48 | |
| 49 1. General information and availability | |
| 50 2. Python in the real world | |
|
3023
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
51 3. Building Python and Other Known Bugs |
| 1529 | 52 4. Programming in Python |
| 53 5. Extending Python | |
| 54 6. Python's design | |
| 55 7. Using Python on non-UNIX platforms | |
| 56 | |
| 57 To find the start of a particular chapter, search for the chapter number | |
| 58 followed by a dot and a space at the beginning of a line (e.g. to | |
| 59 find chapter 4 in vi, type /^4\. /). | |
| 60 | |
| 61 Here's an overview of the questions per chapter: | |
| 62 | |
| 63 1. General information and availability | |
| 64 1.1. Q. What is Python? | |
| 65 1.2. Q. Why is it called Python? | |
| 66 1.3. Q. How do I obtain a copy of the Python source? | |
| 67 1.4. Q. How do I get documentation on Python? | |
|
1657
f02a46754f50
Added stuff about indentation
Guido van Rossum <guido@python.org>
parents:
1613
diff
changeset
|
68 1.5. Q. Are there other ftp sites that mirror the Python distribution? |
|
f02a46754f50
Added stuff about indentation
Guido van Rossum <guido@python.org>
parents:
1613
diff
changeset
|
69 1.6. Q. Is there a newsgroup or mailing list devoted to Python? |
| 2048 | 70 1.7. Q. Is there a WWW page devoted to Python? |
|
2526
d1123b10cf23
removed GPL mumbo jumbo
Guido van Rossum <guido@python.org>
parents:
2301
diff
changeset
|
71 1.8. Q. Is the Python documentation available on the WWW? |
|
d1123b10cf23
removed GPL mumbo jumbo
Guido van Rossum <guido@python.org>
parents:
2301
diff
changeset
|
72 1.9. Q. Is there a book on Python, or will there be one out soon? |
|
d1123b10cf23
removed GPL mumbo jumbo
Guido van Rossum <guido@python.org>
parents:
2301
diff
changeset
|
73 1.10. Q. Are there any published articles about Python that I can quote? |
|
d1123b10cf23
removed GPL mumbo jumbo
Guido van Rossum <guido@python.org>
parents:
2301
diff
changeset
|
74 1.11. Q. Are there short introductory papers or talks on Python? |
|
d1123b10cf23
removed GPL mumbo jumbo
Guido van Rossum <guido@python.org>
parents:
2301
diff
changeset
|
75 1.12. Q. How does the Python version numbering scheme work? |
|
d1123b10cf23
removed GPL mumbo jumbo
Guido van Rossum <guido@python.org>
parents:
2301
diff
changeset
|
76 1.13. Q. How do I get a beta test version of Python? |
|
3126
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
77 1.14. Q. Are there copyright restrictions on the use of Python? |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
78 1.15. Q. Why was Python created in the first place? |
| 1529 | 79 |
| 80 2. Python in the real world | |
| 81 2.1. Q. How many people are using Python? | |
| 82 2.2. Q. Have any significant projects been done in Python? | |
| 83 2.3. Q. Are there any commercial projects going on using Python? | |
|
1533
995a8ef4a5c0
Changes for release of 1.0.0
Guido van Rossum <guido@python.org>
parents:
1529
diff
changeset
|
84 2.4. Q. How stable is Python? |
|
4250
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
85 2.5. Q. What new developments are expected for Python in the future? |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
86 2.6. Q. Is it reasonable to propose incompatible changes to Python? |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
87 2.7. Q. What is the future of Python? |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
88 2.8. Q. What is the PSA, anyway? |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
89 2.9. Q. How do I join the PSA? |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
90 2.10. Q. What are the benefits of joining the PSA? |
| 1529 | 91 |
|
3023
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
92 3. Building Python and Other Known Bugs |
|
1547
0efa240b1dbc
At the release of 1.0.1
Guido van Rossum <guido@python.org>
parents:
1541
diff
changeset
|
93 3.1. Q. Is there a test set? |
|
0efa240b1dbc
At the release of 1.0.1
Guido van Rossum <guido@python.org>
parents:
1541
diff
changeset
|
94 3.2. Q. When running the test set, I get complaints about floating point |
| 1529 | 95 operations, but when playing with floating point operations I cannot |
| 96 find anything wrong with them. | |
|
2716
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
97 3.3. Q. Link errors after rerunning the configure script. |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
98 3.4. Q. The python interpreter complains about options passed to a |
|
1541
630e03109c63
Released version 1.4; out after 1.0.0 is released...
Guido van Rossum <guido@python.org>
parents:
1535
diff
changeset
|
99 script (after the script name). |
|
2716
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
100 3.5. Q. When building on the SGI, make tries to run python to create |
|
1579
021daabe69d8
Updated for existence of newsgroup and various misc things
Guido van Rossum <guido@python.org>
parents:
1547
diff
changeset
|
101 glmodule.c, but python hasn't been built or installed yet. |
|
4250
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
102 3.6. Q. I use VPATH but some targets are built in the source directory. |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
103 3.7. Q. Trouble building or linking with the GNU readline library. |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
104 3.8. Q. Trouble with socket I/O on older Linux 1.x versions. |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
105 3.9. Q. Trouble with prototypes on Ultrix. |
|
4376
d4f64fc42d84
Toss Q 3.10 on posix.listdir on NeXT. Add revived vpApp.
Guido van Rossum <guido@python.org>
parents:
4278
diff
changeset
|
106 3.10. Q. Other trouble building Python on platform X. |
|
d4f64fc42d84
Toss Q 3.10 on posix.listdir on NeXT. Add revived vpApp.
Guido van Rossum <guido@python.org>
parents:
4278
diff
changeset
|
107 3.11. Q. How to configure dynamic loading on Linux. |
|
4408
6c771ea38eee
Added item about bug in Slackware96 libdl.
Guido van Rossum <guido@python.org>
parents:
4376
diff
changeset
|
108 3.12. Q: I can't get shared modules to work on Linux 2.0 (Slackware96)? |
|
4542
652303ef926b
Added Q. about enabling *shared* on Linux.
Guido van Rossum <guido@python.org>
parents:
4480
diff
changeset
|
109 3.13. Q: Trouble when making modules shared on Linux. |
|
652303ef926b
Added Q. about enabling *shared* on Linux.
Guido van Rossum <guido@python.org>
parents:
4480
diff
changeset
|
110 3.14. Q. How to use threads on Linux. |
|
652303ef926b
Added Q. about enabling *shared* on Linux.
Guido van Rossum <guido@python.org>
parents:
4480
diff
changeset
|
111 3.15. Q. Errors when linking with a shared library containing C++ code. |
|
652303ef926b
Added Q. about enabling *shared* on Linux.
Guido van Rossum <guido@python.org>
parents:
4480
diff
changeset
|
112 3.16. Q. I built with tkintermodule.c enabled but get "Tkinter not found". |
|
652303ef926b
Added Q. about enabling *shared* on Linux.
Guido van Rossum <guido@python.org>
parents:
4480
diff
changeset
|
113 3.17. Q. I built with Tk 4.0 but Tkinter complains about the Tk version. |
|
652303ef926b
Added Q. about enabling *shared* on Linux.
Guido van Rossum <guido@python.org>
parents:
4480
diff
changeset
|
114 3.18. Q. Link errors for Tcl/Tk symbols when linking with Tcl/Tk. |
|
652303ef926b
Added Q. about enabling *shared* on Linux.
Guido van Rossum <guido@python.org>
parents:
4480
diff
changeset
|
115 3.19. Q. I configured and built Python for Tcl/Tk but "import Tkinter" |
|
4250
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
116 fails. |
|
4542
652303ef926b
Added Q. about enabling *shared* on Linux.
Guido van Rossum <guido@python.org>
parents:
4480
diff
changeset
|
117 3.20. Q. Tk doesn't work right on DEC Alpha. |
|
652303ef926b
Added Q. about enabling *shared* on Linux.
Guido van Rossum <guido@python.org>
parents:
4480
diff
changeset
|
118 3.21. Q. Several common system calls are missing from the posix module. |
|
652303ef926b
Added Q. about enabling *shared* on Linux.
Guido van Rossum <guido@python.org>
parents:
4480
diff
changeset
|
119 3.22. Q. ImportError: No module named string, on MS Windows. |
|
652303ef926b
Added Q. about enabling *shared* on Linux.
Guido van Rossum <guido@python.org>
parents:
4480
diff
changeset
|
120 3.23. Q. Core dump on SGI when using the gl module. |
| 1529 | 121 |
| 122 4. Programming in Python | |
|
1541
630e03109c63
Released version 1.4; out after 1.0.0 is released...
Guido van Rossum <guido@python.org>
parents:
1535
diff
changeset
|
123 4.1. Q. Is there a source code level debugger with breakpoints, step, |
|
630e03109c63
Released version 1.4; out after 1.0.0 is released...
Guido van Rossum <guido@python.org>
parents:
1535
diff
changeset
|
124 etc.? |
|
630e03109c63
Released version 1.4; out after 1.0.0 is released...
Guido van Rossum <guido@python.org>
parents:
1535
diff
changeset
|
125 4.2. Q. Can I create an object class with some methods implemented in |
| 1529 | 126 C and others in Python (e.g. through inheritance)? (Also phrased as: |
| 127 Can I use a built-in type as base class?) | |
|
1541
630e03109c63
Released version 1.4; out after 1.0.0 is released...
Guido van Rossum <guido@python.org>
parents:
1535
diff
changeset
|
128 4.3. Q. Is there a curses/termcap package for Python? |
|
630e03109c63
Released version 1.4; out after 1.0.0 is released...
Guido van Rossum <guido@python.org>
parents:
1535
diff
changeset
|
129 4.4. Q. Is there an equivalent to C's onexit() in Python? |
|
630e03109c63
Released version 1.4; out after 1.0.0 is released...
Guido van Rossum <guido@python.org>
parents:
1535
diff
changeset
|
130 4.5. Q. When I define a function nested inside another function, the |
| 1529 | 131 nested function seemingly can't access the local variables of the |
| 132 outer function. What is going on? How do I pass local data to a | |
| 133 nested function? | |
|
1541
630e03109c63
Released version 1.4; out after 1.0.0 is released...
Guido van Rossum <guido@python.org>
parents:
1535
diff
changeset
|
134 4.6. Q. How do I iterate over a sequence in reverse order? |
|
630e03109c63
Released version 1.4; out after 1.0.0 is released...
Guido van Rossum <guido@python.org>
parents:
1535
diff
changeset
|
135 4.7. Q. My program is too slow. How do I speed it up? |
|
630e03109c63
Released version 1.4; out after 1.0.0 is released...
Guido van Rossum <guido@python.org>
parents:
1535
diff
changeset
|
136 4.8. Q. When I have imported a module, then edit it, and import it |
| 1529 | 137 again (into the same Python process), the changes don't seem to take |
| 138 place. What is going on? | |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
139 4.9. Q. How do I find the current module name? |
| 2048 | 140 4.10. Q. I have a module in which I want to execute some extra code |
| 141 when it is run as a script. How do I find out whether I am running as | |
| 142 a script? | |
| 143 4.11. Q. I try to run a program from the Demo directory but it fails | |
| 144 with ImportError: No module named ...; what gives? | |
| 1942 | 145 4.12. Q. I have successfully built Python with STDWIN but it can't |
| 146 find some modules (e.g. stdwinevents). | |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
147 4.13. Q. What GUI toolkits exist for Python? |
| 1942 | 148 4.14. Q. Are there any interfaces to database packages in Python? |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
149 4.15. Q. Is it possible to write obfuscated one-liners in Python? |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
150 4.16. Q. Is there an equivalent of C's "?:" ternary operator? |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
151 4.17. Q. My class defines __del__ but it is not called when I delete the |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
152 object. |
| 2048 | 153 4.18. Q. How do I change the shell environment for programs called |
| 154 using os.popen() or os.system()? Changing os.environ doesn't work. | |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
155 4.19. Q. What is a class? |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
156 4.20. Q. What is a method? |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
157 4.21. Q. What is self? |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
158 4.22. Q. What is a unbound method? |
| 2048 | 159 4.23. Q. How do I call a method defined in a base class from a derived |
| 160 class that overrides it? | |
| 161 4.24. Q. How do I call a method from a base class without using the | |
| 162 name of the base class? | |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
163 4.25. Q. How can I organize my code to make it easier to change the base |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
164 class? |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
165 4.26. Q. How can I find the methods or attributes of an object? |
| 1942 | 166 4.27. Q. I can't seem to use os.read() on a pipe created with os.popen(). |
| 167 4.28. Q. How can I create a stand-alone binary from a Python script? | |
|
2716
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
168 4.29. Q. What WWW tools are there for Python? |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
169 4.30. Q. How do I run a subprocess with pipes connected to both input |
|
2208
c68a0113b75a
intermediate version -- why not...
Guido van Rossum <guido@python.org>
parents:
2048
diff
changeset
|
170 and output? |
|
2716
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
171 4.31. Q. How do I call a function if I have the arguments in a tuple? |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
172 4.32. Q. How do I enable font-lock-mode for Python in Emacs? |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
173 4.33. Q. Is there an inverse to the format operator (a la C's scanf())? |
|
3727
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
174 4.34. Q. Can I have Tk events handled while waiting for I/O? |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
175 4.35. Q. How do I write a function with output parameters (call by reference)? |
|
3865
4591035228a7
Added two new questions; about globals/locals and about recursive imports.
Guido van Rossum <guido@python.org>
parents:
3727
diff
changeset
|
176 4.36. Q. Please explain the rules for local and global variables in Python. |
|
4591035228a7
Added two new questions; about globals/locals and about recursive imports.
Guido van Rossum <guido@python.org>
parents:
3727
diff
changeset
|
177 4.37. Q. How can I have modules that mutually import each other? |
|
4250
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
178 4.38. Q. How do I copy an object in Python? |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
179 4.39. Q. How to implement persistent objects in Python? (Persistent == |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
180 automatically saved to and restored from disk.) |
|
4438
e88b3215e94a
Added question about error from misuse of mangled names.
Guido van Rossum <guido@python.org>
parents:
4408
diff
changeset
|
181 4.40. Q. I try to use __spam and I get an error about _SomeClassName__spam. |
|
4543
e52054440efc
Added os.remove()/unlink(), rmdir(), rename(), and [f]truncate().
Guido van Rossum <guido@python.org>
parents:
4542
diff
changeset
|
182 4.41. Q. How do I delete a file? And other file questions. |
|
5200
024e738674a5
Added Q. about HTTP/1.1.
Guido van Rossum <guido@python.org>
parents:
5157
diff
changeset
|
183 4.42. Q. How to modify urllib or httplib to support HTTP/1.1? |
|
5201
5878a5af3148
Added note about adding \n to source for exec and compile.
Guido van Rossum <guido@python.org>
parents:
5200
diff
changeset
|
184 4.43. Q. Unexplicable syntax errors in compile() or exec. |
|
5215
f70042c19c57
Added two new questions about number conversions.
Guido van Rossum <guido@python.org>
parents:
5201
diff
changeset
|
185 4.44. Q. How do I convert a string to a number? |
|
f70042c19c57
Added two new questions about number conversions.
Guido van Rossum <guido@python.org>
parents:
5201
diff
changeset
|
186 4.45. Q. How do I convert a number to a string? |
| 1529 | 187 |
| 188 5. Extending Python | |
| 189 5.1. Q. Can I create my own functions in C? | |
| 190 5.2. Q. Can I create my own functions in C++? | |
| 1663 | 191 5.3. Q. How can I execute arbitrary Python statements from C? |
| 192 5.4. Q. How can I evaluate an arbitrary Python expression from C? | |
| 193 5.5. Q. How do I extract C values from a Python object? | |
| 194 5.6. Q. How do I use mkvalue() to create a tuple of arbitrary length? | |
|
4250
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
195 5.7. Q. How do I call an object's method from C? |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
196 5.8. Q. How do I catch the output from print_error()? |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
197 5.9. Q. How do I access a module written in Python from C? |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
198 5.10. Q. How do I interface to C++ objects from Python? |
| 1529 | 199 |
| 200 6. Python's design | |
|
4250
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
201 6.1. Q. Why isn't there a switch or case statement in Python? |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
202 6.2. Q. Why does Python use indentation for grouping of statements? |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
203 6.3. Q. Why are Python strings immutable? |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
204 6.4. Q. Why don't strings have methods like index() or sort(), like |
|
1740
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
205 lists? |
|
4250
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
206 6.5. Q. Why does Python use methods for some functionality |
|
1740
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
207 (e.g. list.index()) but functions for other (e.g. len(list))? |
|
4250
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
208 6.6. Q. Why can't I derive a class from built-in types (e.g. lists or |
|
1740
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
209 files)? |
|
4250
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
210 6.7. Q. Why must 'self' be declared and used explicitly in method |
|
1740
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
211 definitions and calls? |
|
4250
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
212 6.8. Q. Can't you emulate threads in the interpreter instead of |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
213 relying on an OS-specific thread implementation? |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
214 6.9. Q. Why can't lambda forms contain statements? |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
215 6.10. Q. Why don't lambdas have access to variables defined in the |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
216 containing scope? |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
217 6.11. Q. Why can't recursive functions be defined inside other functions? |
| 1942 | 218 6.12. Q. Why is there no more efficient way of iterating over a dictionary |
| 219 than first constructing the list of keys()? | |
|
3023
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
220 6.13. Q. Can Python be compiled to machine code, C or some other language? |
|
3126
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
221 6.14. Q. Why doesn't Python use proper garbage collection? |
| 1529 | 222 |
| 223 7. Using Python on non-UNIX platforms | |
|
1547
0efa240b1dbc
At the release of 1.0.1
Guido van Rossum <guido@python.org>
parents:
1541
diff
changeset
|
224 7.1. Q. Is there a Mac version of Python? |
|
4278
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
225 7.2. Q. Are there DOS and Windows versions of Python? |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
226 7.3. Q. Is there an OS/2 version of Python? |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
227 7.4. Q. Is there a VMS version of Python? |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
228 7.5. Q. What about IBM mainframes, or other non-UNIX platforms? |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
229 7.6. Q. Where are the source or Makefiles for the non-UNIX versions? |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
230 7.7. Q. What is the status and support for the non-UNIX versions? |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
231 7.8. Q. I have a PC version but it appears to be only a binary. |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
232 Where's the library? |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
233 7.9. Q. Where's the documentation for the Mac or PC version? |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
234 7.10. Q. The Mac (PC) version doesn't seem to have any facilities for |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
235 creating or editing programs apart from entering it interactively, and |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
236 there seems to be no way to save code that was entered interactively. |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
237 How do I create a Python program on the Mac (PC)? |
| 1529 | 238 |
| 239 To find a particular question, search for the question number followed | |
| 240 by a dot, a space, and a Q at the beginning of a line (e.g. to find | |
| 241 question 4.2 in vi, type /^4\.2\. Q/). | |
| 242 | |
| 243 | |
| 244 1. General information and availability | |
|
3023
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
245 ======================================= |
| 1529 | 246 |
| 247 1.1. Q. What is Python? | |
| 248 | |
| 249 A. Python is an interpreted, interactive, object-oriented programming | |
| 250 language. It incorporates modules, exceptions, dynamic typing, very | |
| 251 high level dynamic data types, and classes. Python combines | |
| 252 remarkable power with very clear syntax. It has interfaces to many | |
| 253 system calls and libraries, as well as to various window systems, and | |
| 254 is extensible in C or C++. It is also usable as an extension language | |
| 255 for applications that need a programmable interface. Finally, Python | |
| 2048 | 256 is portable: it runs on many brands of UNIX, on the Mac, and on PCs |
| 257 under MS-DOS, Windows, Windows NT, and OS/2. | |
| 1529 | 258 |
| 259 To find out more, the best thing to do is to start reading the | |
| 260 tutorial from the documentation set (see a few questions further | |
| 261 down). | |
| 262 | |
| 263 1.2. Q. Why is it called Python? | |
| 264 | |
|
2208
c68a0113b75a
intermediate version -- why not...
Guido van Rossum <guido@python.org>
parents:
2048
diff
changeset
|
265 A. Apart from being a computer scientist, I'm also a fan of "Monty |
| 1529 | 266 Python's Flying Circus" (a BBC comedy series from the seventies, in |
|
1579
021daabe69d8
Updated for existence of newsgroup and various misc things
Guido van Rossum <guido@python.org>
parents:
1547
diff
changeset
|
267 the -- unlikely -- case you didn't know). It occurred to me one day |
|
021daabe69d8
Updated for existence of newsgroup and various misc things
Guido van Rossum <guido@python.org>
parents:
1547
diff
changeset
|
268 that I needed a name that was short, unique, and slightly mysterious. |
|
021daabe69d8
Updated for existence of newsgroup and various misc things
Guido van Rossum <guido@python.org>
parents:
1547
diff
changeset
|
269 And I happened to be reading some scripts from the series at the |
|
021daabe69d8
Updated for existence of newsgroup and various misc things
Guido van Rossum <guido@python.org>
parents:
1547
diff
changeset
|
270 time... So then I decided to call my language Python. But Python is |
|
021daabe69d8
Updated for existence of newsgroup and various misc things
Guido van Rossum <guido@python.org>
parents:
1547
diff
changeset
|
271 not a joke. And don't you associate it with dangerous reptiles |
| 2048 | 272 either! (If you need an icon, use an image of the 16-ton weight from |
| 273 the TV series or of a can of SPAM :-) | |
| 1529 | 274 |
| 275 1.3. Q. How do I obtain a copy of the Python source? | |
| 276 | |
| 2048 | 277 A. The latest complete Python source distribution is always available |
| 278 by anonymous ftp, e.g. | |
|
4250
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
279 <URL:ftp://ftp.python.org/pub/python/src/python1.3.tar.gz>. It is a |
|
2661
b4fd48e3a3b8
changed path references
Guido van Rossum <guido@python.org>
parents:
2660
diff
changeset
|
280 gzipped tar file containing the complete C source, LaTeX |
|
b4fd48e3a3b8
changed path references
Guido van Rossum <guido@python.org>
parents:
2660
diff
changeset
|
281 documentation, Python library modules, example programs, and several |
|
b4fd48e3a3b8
changed path references
Guido van Rossum <guido@python.org>
parents:
2660
diff
changeset
|
282 useful pieces of freely distributable software. This will compile and |
|
b4fd48e3a3b8
changed path references
Guido van Rossum <guido@python.org>
parents:
2660
diff
changeset
|
283 run out of the box on most UNIX platforms. (See section 7 for |
|
b4fd48e3a3b8
changed path references
Guido van Rossum <guido@python.org>
parents:
2660
diff
changeset
|
284 non-UNIX information.) |
| 2048 | 285 |
|
4250
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
286 Sometimes beta versions of a newer release are available; check the |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
287 subdirectory "beta" of the above-mentioned URL (i.e. |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
288 <URL:ftp://ftp.python.org/pub/python/src/beta/>). (At the time of |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
289 writing, beta3 for Python 1.4 is available there, and should be |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
290 checked before reporting problems with version 1.3.) |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
291 |
| 2048 | 292 Occasionally a set of patches is issued which has to be applied using |
| 293 the patch program. These patches are placed in the same directory, | |
|
2716
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
294 e.g. <URL:ftp://ftp.python.org/pub/python/src/patch1.1.1>. (At the time |
|
4250
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
295 of writing, no patches exist.) |
| 2048 | 296 |
| 297 An index of said ftp directory can be found in the file INDEX. An | |
| 298 HTML version of the index can be found in the file index.html, | |
|
2716
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
299 <URL:ftp://ftp.python.org/pub/python/index.html>. |
| 1529 | 300 |
| 301 1.4. Q. How do I get documentation on Python? | |
| 302 | |
|
2526
d1123b10cf23
removed GPL mumbo jumbo
Guido van Rossum <guido@python.org>
parents:
2301
diff
changeset
|
303 A. The LaTeX source for the documentation is part of the source |
|
d1123b10cf23
removed GPL mumbo jumbo
Guido van Rossum <guido@python.org>
parents:
2301
diff
changeset
|
304 distribution. If you don't have LaTeX, the latest Python |
|
d1123b10cf23
removed GPL mumbo jumbo
Guido van Rossum <guido@python.org>
parents:
2301
diff
changeset
|
305 documentation set is always available by anonymous ftp, e.g. |
|
2716
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
306 <URL:ftp://ftp.python.org/pub/python/doc/postscript.tar.gz>. It is a |
| 2048 | 307 gzipped tar file containing PostScript files of the reference manual, |
|
1740
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
308 the library manual, and the tutorial. Note that the library manual is |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
309 the most important one of the set, as much of Python's power stems |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
310 from the standard or built-in types, functions and modules, all of |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
311 which are described here. PostScript for a high-level description of |
|
2526
d1123b10cf23
removed GPL mumbo jumbo
Guido van Rossum <guido@python.org>
parents:
2301
diff
changeset
|
312 Python is in the file nluug-paper.ps (a separate file on the ftp |
|
d1123b10cf23
removed GPL mumbo jumbo
Guido van Rossum <guido@python.org>
parents:
2301
diff
changeset
|
313 site). |
| 1529 | 314 |
|
1657
f02a46754f50
Added stuff about indentation
Guido van Rossum <guido@python.org>
parents:
1613
diff
changeset
|
315 1.5. Q. Are there other ftp sites that mirror the Python distribution? |
|
f02a46754f50
Added stuff about indentation
Guido van Rossum <guido@python.org>
parents:
1613
diff
changeset
|
316 |
| 2048 | 317 A. The following anonymous ftp sites keep mirrors of the Python |
| 318 distribution: | |
| 1529 | 319 |
|
3207
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
320 USA: |
|
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
321 |
|
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
322 <URL:ftp://ftp.python.org/pub/python/> |
| 2048 | 323 <URL:ftp://gatekeeper.dec.com/pub/plan/python/> |
|
3207
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
324 <URL:ftp://ftp.uu.net/languages/python/> |
| 2048 | 325 <URL:ftp://ftp.wustl.edu/graphics/graphics/sgi-stuff/python/> |
|
3207
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
326 <URL:ftp://ftp.sterling.com/programming/languages/python/> |
|
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
327 <URL:ftp://uiarchive.cso.uiuc.edu/pub/lang/python/> |
|
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
328 <URL:ftp://ftp.pht.com/mirrors/python/python/> |
|
5156
417462ab8b00
Added new ftp mirror site ftp://ftp.cdrom.com/pub/python/ (Walnut Creek CDROM).
Guido van Rossum <guido@python.org>
parents:
5127
diff
changeset
|
329 <URL:ftp://ftp.cdrom.com/pub/python/> |
|
3207
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
330 |
|
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
331 Europe: |
|
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
332 |
|
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
333 <URL:ftp://ftp.cwi.nl/pub/python/> |
| 2048 | 334 <URL:ftp://ftp.funet.fi/pub/languages/python/> |
| 335 <URL:ftp://ftp.sunet.se/pub/lang/python/> | |
| 2855 | 336 <URL:ftp://unix.hensa.ac.uk/mirrors/uunet/languages/python/> |
|
3023
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
337 <URL:ftp://ftp.ibp.fr/pub/python/> |
|
4589
961bf9a200dd
New URL for Swiss ftp mirror.
Guido van Rossum <guido@python.org>
parents:
4563
diff
changeset
|
338 <URL:ftp://sunsite.cnlab-switch.ch/mirror/python/> |
| 2855 | 339 <URL:ftp://ftp.informatik.tu-muenchen.de/pub/comp/programming/languages/python/> |
| 1529 | 340 |
|
3207
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
341 Australia: |
|
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
342 |
|
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
343 <URL:ftp://ftp.dstc.edu.au/pub/python/> |
|
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
344 |
| 2048 | 345 Or try archie on the string "python". |
| 1529 | 346 |
|
1657
f02a46754f50
Added stuff about indentation
Guido van Rossum <guido@python.org>
parents:
1613
diff
changeset
|
347 1.6. Q. Is there a newsgroup or mailing list devoted to Python? |
| 1529 | 348 |
| 2048 | 349 A. There is a newsgroup, comp.lang.python <URL:news:comp.lang.python>, |
| 350 and a mailing list. The newsgroup and mailing list are gatewayed into | |
| 351 each other -- if you can read news it's unnecessary to subscribe to | |
| 352 the mailing list. Send e-mail to <python-list-request@cwi.nl> to | |
|
2661
b4fd48e3a3b8
changed path references
Guido van Rossum <guido@python.org>
parents:
2660
diff
changeset
|
353 (un)subscribe to the mailing list. Hypermail archives of (nearly) |
|
b4fd48e3a3b8
changed path references
Guido van Rossum <guido@python.org>
parents:
2660
diff
changeset
|
354 everything posted to the mailing list (and thus the newsgroup) are |
|
b4fd48e3a3b8
changed path references
Guido van Rossum <guido@python.org>
parents:
2660
diff
changeset
|
355 available on our WWW server, |
| 2048 | 356 <URL:http://www.cwi.nl/~guido/hypermail/index.html>. The raw archives |
| 357 are also available by ftp, e.g. | |
|
2716
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
358 <URL:ftp://ftp.python.org/pub/python/mail/mailinglist.gz>. The |
|
2661
b4fd48e3a3b8
changed path references
Guido van Rossum <guido@python.org>
parents:
2660
diff
changeset
|
359 uncompressed versions of these files can be read with the standard |
|
b4fd48e3a3b8
changed path references
Guido van Rossum <guido@python.org>
parents:
2660
diff
changeset
|
360 UNIX Mail program ("Mail -f file") or with nn ("nn file"). To read |
| 3018 | 361 them using MH, you could use "inc -file file". (The archival service |
| 362 has stopped archiving new articles around the end of April 1995. I | |
| 363 hope to revive it on the PSA server www.python.org sometime in the | |
| 364 future.) | |
| 1529 | 365 |
| 2048 | 366 1.7. Q. Is there a WWW page devoted to Python? |
| 367 | |
|
2716
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
368 A. Yes, <URL:http://www.python.org/> is the official Python home page. |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
369 At the time of writing, this page is not yet completely operational; |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
370 you may have a look at the old Python home page: |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
371 <URL:http://www.cwi.nl/~guido/Python.html> or at the U.S. copy: |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
372 <URL:http://www.python.org/~guido/Python.html>. |
| 2048 | 373 |
|
2526
d1123b10cf23
removed GPL mumbo jumbo
Guido van Rossum <guido@python.org>
parents:
2301
diff
changeset
|
374 1.8. Q. Is the Python documentation available on the WWW? |
|
d1123b10cf23
removed GPL mumbo jumbo
Guido van Rossum <guido@python.org>
parents:
2301
diff
changeset
|
375 |
|
2716
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
376 A. Yes, see <URL:http://www.python.org/> (Python's home page). It |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
377 contains pointers to hypertext versions of the whole documentation set |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
378 (as hypertext, not just PostScript). |
| 1529 | 379 |
|
2526
d1123b10cf23
removed GPL mumbo jumbo
Guido van Rossum <guido@python.org>
parents:
2301
diff
changeset
|
380 If you wish to browse this collection of HTML files on your own |
|
d1123b10cf23
removed GPL mumbo jumbo
Guido van Rossum <guido@python.org>
parents:
2301
diff
changeset
|
381 machine, it is available bundled up by anonymous ftp, |
|
2716
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
382 e.g. <URL:ftp://ftp.python.org/pub/python/doc/html.tar.gz>. |
| 1529 | 383 |
|
2526
d1123b10cf23
removed GPL mumbo jumbo
Guido van Rossum <guido@python.org>
parents:
2301
diff
changeset
|
384 An Emacs-INFO set containing the library manual is also available by |
|
2716
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
385 ftp, e.g. <URL:ftp://ftp.python.org/pub/python/doc/lib-info.tar.gz>. |
|
2526
d1123b10cf23
removed GPL mumbo jumbo
Guido van Rossum <guido@python.org>
parents:
2301
diff
changeset
|
386 |
|
d1123b10cf23
removed GPL mumbo jumbo
Guido van Rossum <guido@python.org>
parents:
2301
diff
changeset
|
387 1.9. Q. Is there a book on Python, or will there be one out soon? |
|
d1123b10cf23
removed GPL mumbo jumbo
Guido van Rossum <guido@python.org>
parents:
2301
diff
changeset
|
388 |
| 2855 | 389 A. Mark Lutz is writing a Python book for O'Reilly and Associates, to |
| 390 be published early 1996. See the outline (in PostScript): | |
| 391 <URL:http://www.python.org/workshops/1995-05/outlinep.eps>. | |
|
2526
d1123b10cf23
removed GPL mumbo jumbo
Guido van Rossum <guido@python.org>
parents:
2301
diff
changeset
|
392 |
|
d1123b10cf23
removed GPL mumbo jumbo
Guido van Rossum <guido@python.org>
parents:
2301
diff
changeset
|
393 1.10. Q. Are there any published articles about Python that I can quote? |
| 1529 | 394 |
| 395 A. So far the only refereed and published article that describes | |
| 396 Python in some detail is: | |
| 397 | |
| 398 Guido van Rossum and Jelke de Boer, "Interactively Testing Remote | |
| 399 Servers Using the Python Programming Language", CWI Quarterly, Volume | |
| 400 4, Issue 4 (December 1991), Amsterdam, pp 283-303. | |
| 401 | |
| 402 LaTeX source for this paper is available as part of the Python source | |
| 403 distribution. | |
| 404 | |
|
3126
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
405 See also the next section (supposedly Aaron Watters' paper has been |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
406 refereed). |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
407 |
|
2526
d1123b10cf23
removed GPL mumbo jumbo
Guido van Rossum <guido@python.org>
parents:
2301
diff
changeset
|
408 1.11. Q. Are there short introductory papers or talks on Python? |
| 2048 | 409 |
|
3126
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
410 A. A recent, very entertaining introduction to Python is the tutorial by |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
411 Aaron Watters in UnixWorld Online: |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
412 |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
413 Aaron R. Watters: "The What, Why, Who, and Where of Python", |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
414 <URL:http://www.wcmh.com/uworld/archives/95/tutorial/005.html> |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
415 |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
416 An olded paper is: |
| 1529 | 417 |
| 418 Guido van Rossum, "An Introduction to Python for UNIX/C | |
| 419 Programmers", in the proceedings of the NLUUG najaarsconferentie | |
| 1942 | 420 1993 (dutch UNIX users group meeting November 1993). |
| 2048 | 421 |
| 1529 | 422 PostScript for this paper and for the slides used for the accompanying |
| 2048 | 423 presentation is available by ftp as |
|
2716
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
424 <URL:ftp://ftp.python.org/pub/python/doc/nluug-paper.ps> and |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
425 <URL:ftp://ftp.python.org/pub/python/doc/nluug-slides.ps>, respectively. |
| 1529 | 426 |
| 2048 | 427 Slides for a talk on Python that I gave at the Usenix Symposium on |
|
3126
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
428 Very High Level Languages in Santa Fe, NM, USA in October 1994 are |
|
2716
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
429 available as <URL:ftp://ftp.python.org/pub/python/doc/vhll-slides.ps>. |
| 2048 | 430 |
|
2526
d1123b10cf23
removed GPL mumbo jumbo
Guido van Rossum <guido@python.org>
parents:
2301
diff
changeset
|
431 1.12. Q. How does the Python version numbering scheme work? |
|
1533
995a8ef4a5c0
Changes for release of 1.0.0
Guido van Rossum <guido@python.org>
parents:
1529
diff
changeset
|
432 |
|
3126
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
433 A. Python versions are numbered A.B.C or A.B. A is the major version |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
434 number -- it is only incremented for major changes in functionality or |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
435 source structure. B is the minor version number, incremented for less |
|
1533
995a8ef4a5c0
Changes for release of 1.0.0
Guido van Rossum <guido@python.org>
parents:
1529
diff
changeset
|
436 earth-shattering changes to a release. C is the patchlevel -- it is |
|
3126
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
437 incremented for each new patch release. Not all releases have patch |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
438 releases. Note that in the past, patches have added significant |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
439 changes; in fact the changeover from 0.9.9 to 1.0.0 was the first time |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
440 that either A or B changed! |
|
1533
995a8ef4a5c0
Changes for release of 1.0.0
Guido van Rossum <guido@python.org>
parents:
1529
diff
changeset
|
441 |
|
4250
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
442 Beta versions have an additional suffix of "betaN" for some small |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
443 number N. Note that (for instance) all versions labeled 1.4betaN |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
444 *precede* the actual release of 1.4. 1.4b3 is short for 1.4beta3. |
|
2526
d1123b10cf23
removed GPL mumbo jumbo
Guido van Rossum <guido@python.org>
parents:
2301
diff
changeset
|
445 |
|
d1123b10cf23
removed GPL mumbo jumbo
Guido van Rossum <guido@python.org>
parents:
2301
diff
changeset
|
446 1.13. Q. How do I get a beta test version of Python? |
|
d1123b10cf23
removed GPL mumbo jumbo
Guido van Rossum <guido@python.org>
parents:
2301
diff
changeset
|
447 |
|
3126
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
448 A. If there are any beta releases, they are published in the normal |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
449 source directory (e.g. <URL:ftp://ftp.python.org/pub/python/src/>). |
|
1579
021daabe69d8
Updated for existence of newsgroup and various misc things
Guido van Rossum <guido@python.org>
parents:
1547
diff
changeset
|
450 |
|
3126
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
451 1.14. Q. Are there copyright restrictions on the use of Python? |
| 1663 | 452 |
| 453 A. Hardly. You can do anything you want with the source, as long as | |
| 2048 | 454 you leave the copyrights in, and display those copyrights in any |
| 455 documentation about Python that you produce. Also, don't use the | |
| 456 author's institute's name in publicity without prior written | |
| 457 permission, and don't hold them responsible for anything (read the | |
| 458 actual copyright for a precise legal wording). | |
| 459 | |
| 460 In particular, if you honor the copyright rules, it's OK to use Python | |
| 461 for commercial use, to sell copies of Python in source or binary form, | |
| 462 or to sell products that enhance Python or incorporate Python (or part | |
| 463 of it) in some form. I would still like to know about all commercial | |
| 464 use of Python! | |
|
1579
021daabe69d8
Updated for existence of newsgroup and various misc things
Guido van Rossum <guido@python.org>
parents:
1547
diff
changeset
|
465 |
|
3126
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
466 1.15. Q. Why was Python created in the first place? |
|
2716
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
467 |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
468 A. Here's a *very* brief summary of what got me started: |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
469 |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
470 - I had extensive experience with implementing an interpreted language |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
471 in the ABC group at CWI, and from working with this group I had |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
472 learned a lot about language design. This is the origin of many |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
473 Python features, including the use of indentation for statement |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
474 grouping and the inclusion of very-high-level data types (although the |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
475 details are all different in Python). |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
476 |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
477 - I had a number of gripes about the ABC language, but also liked many |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
478 of its features. It was impossible to extend the ABC language (or its |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
479 implementation) to remedy my complaints -- in fact its lack of |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
480 extensibility was one of its biggest problems. |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
481 |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
482 - I had some experience with using Modula-2+ and talked with the |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
483 designers of Modula-3 (and read the M3 report). M3 is the origin of |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
484 the syntax and semantics used for exceptions, and some other Python |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
485 features. |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
486 |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
487 - I was working in the Amoeba distributed operating system group at |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
488 CWI. We needed a better way to do system administration than by |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
489 writing either C programs or Bourne shell scripts, since Amoeba had |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
490 its own system call interface which wasn't easily accessible from the |
| 3018 | 491 Bourne shell. My experience with error handling in Amoeba made me |
| 492 acutely aware of the importance of exceptions as a programming | |
| 493 language feature. | |
|
2716
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
494 |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
495 - It occurred to me that a scripting language with a syntax like ABC |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
496 but with access to the Amoeba system calls would fill the need. I |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
497 realized that it would be foolish to write an Amoeba-specific |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
498 language, so I decided that I needed a language that was generally |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
499 extensible. |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
500 |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
501 - During the 1989 Christmas holidays, I had a lot of time on my hand, |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
502 so I decided to give it a try. During the next year, while still |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
503 mostly working on it in my own time, Python was used in the Amoeba |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
504 project with increasing success, and the feedback from colleagues made |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
505 me add many early improvements. |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
506 |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
507 - In February 1991, after just over a year of development, I decided |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
508 to post to USENET. The rest is in the Misc/HISTORY file. |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
509 |
| 1529 | 510 |
| 511 2. Python in the real world | |
| 512 =========================== | |
| 513 | |
| 514 2.1. Q. How many people are using Python? | |
| 515 | |
|
1579
021daabe69d8
Updated for existence of newsgroup and various misc things
Guido van Rossum <guido@python.org>
parents:
1547
diff
changeset
|
516 A. I don't know, but the maximum number of simultaneous subscriptions |
|
021daabe69d8
Updated for existence of newsgroup and various misc things
Guido van Rossum <guido@python.org>
parents:
1547
diff
changeset
|
517 to the Python mailing list before it was gatewayed into the newsgroup |
|
021daabe69d8
Updated for existence of newsgroup and various misc things
Guido van Rossum <guido@python.org>
parents:
1547
diff
changeset
|
518 was about 180 (several of which were local redistribution lists). I |
|
021daabe69d8
Updated for existence of newsgroup and various misc things
Guido van Rossum <guido@python.org>
parents:
1547
diff
changeset
|
519 believe that many active Python users don't bother to subscribe to the |
|
021daabe69d8
Updated for existence of newsgroup and various misc things
Guido van Rossum <guido@python.org>
parents:
1547
diff
changeset
|
520 list, and now that there's a newsgroup the mailing list subscription |
| 1663 | 521 is even less meaningful. I see new names on the newsgroup all the |
| 522 time and my best guess is that there are currently at least several | |
| 523 thousands of users. | |
| 1529 | 524 |
|
3023
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
525 Another statistic is the number of accesses to the Python WWW server. |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
526 Have a look at <URL:http://www.python.org/stats/>. |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
527 |
| 1529 | 528 2.2. Q. Have any significant projects been done in Python? |
| 529 | |
| 530 A. Here at CWI (the home of Python), we have written a 20,000 line | |
| 531 authoring environment for transportable hypermedia presentations, a | |
|
1579
021daabe69d8
Updated for existence of newsgroup and various misc things
Guido van Rossum <guido@python.org>
parents:
1547
diff
changeset
|
532 5,000 line multimedia teleconferencing tool, as well as many many |
|
021daabe69d8
Updated for existence of newsgroup and various misc things
Guido van Rossum <guido@python.org>
parents:
1547
diff
changeset
|
533 smaller programs. |
| 1529 | 534 |
| 535 The University of Virginia uses Python to control a virtual reality | |
| 536 engine. Contact: Matt Conway <conway@virginia.edu>. | |
| 537 | |
| 2048 | 538 The ILU project at Xerox PARC can generate Python glue for ILU |
| 539 interfaces. See <URL:ftp://ftp.parc.xerox.com/pub/ilu/ilu.html>. | |
| 540 | |
|
2660
4eb6ddb9e961
Some more changes for 1.2
Guido van Rossum <guido@python.org>
parents:
2526
diff
changeset
|
541 The University of California, Irvine uses a student administration |
|
4eb6ddb9e961
Some more changes for 1.2
Guido van Rossum <guido@python.org>
parents:
2526
diff
changeset
|
542 system called TELE-Vision written entirely in Python. Contact: Ray |
|
4eb6ddb9e961
Some more changes for 1.2
Guido van Rossum <guido@python.org>
parents:
2526
diff
changeset
|
543 Price <rlprice@uci.edu>. |
|
4eb6ddb9e961
Some more changes for 1.2
Guido van Rossum <guido@python.org>
parents:
2526
diff
changeset
|
544 |
|
3023
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
545 See also the next question. |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
546 |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
547 If you have done a significant project in Python that you'd like to be |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
548 included in the list above, send me email! |
| 1529 | 549 |
| 550 2.3. Q. Are there any commercial projects going on using Python? | |
| 551 | |
|
5157
829c42893181
Remove the list of Python users, replace it with a pointer to the
Guido van Rossum <guido@python.org>
parents:
5156
diff
changeset
|
552 A. Yes, there's lots of commercial activity using Python. See |
|
829c42893181
Remove the list of Python users, replace it with a pointer to the
Guido van Rossum <guido@python.org>
parents:
5156
diff
changeset
|
553 <URL:http://www.python.org/python/Users.html> for a list. |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
554 |
|
1533
995a8ef4a5c0
Changes for release of 1.0.0
Guido van Rossum <guido@python.org>
parents:
1529
diff
changeset
|
555 2.4. Q. How stable is Python? |
| 1529 | 556 |
|
1740
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
557 A. Very stable. While the current version number would suggest it is |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
558 in the early stages of development, in fact new, stable releases |
| 4590 | 559 (numbered 0.9.x through 1.4) have been coming out roughly every 3 to |
| 560 6 or 12 months for the past four years. | |
|
1533
995a8ef4a5c0
Changes for release of 1.0.0
Guido van Rossum <guido@python.org>
parents:
1529
diff
changeset
|
561 |
|
4250
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
562 2.5. Q. What new developments are expected for Python in the future? |
| 1529 | 563 |
| 4590 | 564 A. Follow the newsgroup discussions! The workshop proceedings |
| 565 (<URL:http://www.python.org/workshops/>) may also contain interesting | |
| 566 looks into the future. | |
| 2048 | 567 |
|
4250
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
568 2.6. Q. Is it reasonable to propose incompatible changes to Python? |
|
1740
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
569 |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
570 A. In general, no. There are already millions of lines of Python code |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
571 around the world, so any changes in the language that invalidates more |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
572 than a very small fraction of existing programs has to be frowned |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
573 upon. Even if you can provide a conversion program, there still is |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
574 the problem of updating all documentation. Providing a gradual |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
575 upgrade path is the only way if a feature has to be changed. |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
576 |
|
4250
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
577 2.7. Q. What is the future of Python? |
| 1529 | 578 |
|
3023
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
579 A. If I knew, I'd be rich :-) |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
580 |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
581 Seriously, the formation of the PSA (Pyton Software Activity, see |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
582 <URL:http://www.python.org/psa/>) ensures some kind of support even in |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
583 the (unlikely! event that I'd be hit by a bus (actually, here in the |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
584 US, a car accident would be more likely :-), were to join a nunnery, |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
585 or would be head-hunted. A large number of Python users have become |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
586 experts at Python programming as well as maintenance of the |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
587 implementation, and would easily fill the vacuum created by my |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
588 disappearance. |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
589 |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
590 In the mean time, I have no plans to disappear -- rather, I am |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
591 committed to improving Python, and my current benefactor, CNRI (see |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
592 <URL:http://www.cnri.reston.va.us>) is just as committed to continue |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
593 its support of Python and the PSA. In fact, we have great plans for |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
594 Python -- we just can't tell yet! |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
595 |
|
4250
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
596 2.8. Q. What is the PSA, anyway? |
|
3126
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
597 |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
598 A. The Python Software Activity <URL:http://www.python.org/psa/> was |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
599 created by a number of Python aficionados who want Python to be more |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
600 than the product and responsibility of a single individual. It has |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
601 found a home at CNRI <URL:http://www.cnri.reston.va.us>. Anybody who |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
602 wishes Python well should join the PSA. |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
603 |
|
4250
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
604 2.9. Q. How do I join the PSA? |
|
3126
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
605 |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
606 A. The full scoop is available on the web, see |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
607 <URL:http://www.python.org/psa/Joining.html>. Summary: send a check |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
608 of at least $50 to CNRI/PSA, 1895 Preston White Drive, Suite 100, in |
|
4221
66913ca7ec47
New email and zip code for Guido
Guido van Rossum <guido@python.org>
parents:
3865
diff
changeset
|
609 Reston, VA 20191. Full-time students pay $25. Companies can join for |
|
3126
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
610 a mere $500. |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
611 |
|
4250
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
612 2.10. Q. What are the benefits of joining the PSA? |
|
3126
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
613 |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
614 A. Like National Public Radio, if not enough people join, Python will |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
615 wither. Your name will be mentioned on the PSA's web server. |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
616 Workshops organized by the PSA <URL:http://www.python.org/workshops/> |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
617 are only accessible to PSA members (you can join at the door). The |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
618 PSA is working on additional benefits, such as reduced prices for |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
619 books and software, and early access to beta versions of Python. |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
620 |
|
3023
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
621 |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
622 3. Building Python and Other Known Bugs |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
623 ======================================= |
| 1529 | 624 |
|
1547
0efa240b1dbc
At the release of 1.0.1
Guido van Rossum <guido@python.org>
parents:
1541
diff
changeset
|
625 3.1. Q. Is there a test set? |
| 1529 | 626 |
| 627 A. Yes, simply do "import testall" (or "import autotest" if you aren't | |
| 628 interested in the output). The standard modules whose name begins | |
| 629 with "test" together comprise the test. The test set doesn't test | |
| 630 *all* features of Python but it goes a long way to confirm that a new | |
| 631 port is actually working. The Makefile contains an entry "make test" | |
| 2048 | 632 which runs the autotest module. NOTE: if "make test" fails, run the |
| 633 tests manually ("import testall") to see what goes wrong before | |
| 634 reporting the error. | |
| 1529 | 635 |
|
1547
0efa240b1dbc
At the release of 1.0.1
Guido van Rossum <guido@python.org>
parents:
1541
diff
changeset
|
636 3.2. Q. When running the test set, I get complaints about floating point |
| 1529 | 637 operations, but when playing with floating point operations I cannot |
| 638 find anything wrong with them. | |
| 639 | |
| 640 A. The test set makes occasional unwarranted assumptions about the | |
| 641 semantics of C floating point operations. Until someone donates a | |
| 642 better floating point test set, you will have to comment out the | |
| 643 offending floating point tests and execute similar tests manually. | |
| 644 | |
|
2716
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
645 3.3. Q. Link errors after rerunning the configure script. |
|
1541
630e03109c63
Released version 1.4; out after 1.0.0 is released...
Guido van Rossum <guido@python.org>
parents:
1535
diff
changeset
|
646 |
|
630e03109c63
Released version 1.4; out after 1.0.0 is released...
Guido van Rossum <guido@python.org>
parents:
1535
diff
changeset
|
647 A. It is generally necessary to run "make clean" after a configuration |
|
630e03109c63
Released version 1.4; out after 1.0.0 is released...
Guido van Rossum <guido@python.org>
parents:
1535
diff
changeset
|
648 change. |
|
630e03109c63
Released version 1.4; out after 1.0.0 is released...
Guido van Rossum <guido@python.org>
parents:
1535
diff
changeset
|
649 |
|
2716
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
650 3.4. Q. The python interpreter complains about options passed to a |
|
1541
630e03109c63
Released version 1.4; out after 1.0.0 is released...
Guido van Rossum <guido@python.org>
parents:
1535
diff
changeset
|
651 script (after the script name). |
|
630e03109c63
Released version 1.4; out after 1.0.0 is released...
Guido van Rossum <guido@python.org>
parents:
1535
diff
changeset
|
652 |
|
630e03109c63
Released version 1.4; out after 1.0.0 is released...
Guido van Rossum <guido@python.org>
parents:
1535
diff
changeset
|
653 A. You are probably linking with GNU getopt, e.g. through -liberty. |
|
1784
a3f199e8bac6
1.12 -- new address for fu-berlin mirror, infoseek uses python, more
Guido van Rossum <guido@python.org>
parents:
1740
diff
changeset
|
654 Don't. The reason for the complaint is that GNU getopt, unlike System |
|
a3f199e8bac6
1.12 -- new address for fu-berlin mirror, infoseek uses python, more
Guido van Rossum <guido@python.org>
parents:
1740
diff
changeset
|
655 V getopt and other getopt implementations, doesn't consider a |
|
a3f199e8bac6
1.12 -- new address for fu-berlin mirror, infoseek uses python, more
Guido van Rossum <guido@python.org>
parents:
1740
diff
changeset
|
656 non-option to be the end of the option list. A quick (and compatible) |
|
a3f199e8bac6
1.12 -- new address for fu-berlin mirror, infoseek uses python, more
Guido van Rossum <guido@python.org>
parents:
1740
diff
changeset
|
657 fix for scripts is to add "--" to the interpreter, like this: |
|
a3f199e8bac6
1.12 -- new address for fu-berlin mirror, infoseek uses python, more
Guido van Rossum <guido@python.org>
parents:
1740
diff
changeset
|
658 |
| 2048 | 659 #! /usr/local/bin/python -- |
|
1784
a3f199e8bac6
1.12 -- new address for fu-berlin mirror, infoseek uses python, more
Guido van Rossum <guido@python.org>
parents:
1740
diff
changeset
|
660 |
|
a3f199e8bac6
1.12 -- new address for fu-berlin mirror, infoseek uses python, more
Guido van Rossum <guido@python.org>
parents:
1740
diff
changeset
|
661 You can also use this interactively: |
|
a3f199e8bac6
1.12 -- new address for fu-berlin mirror, infoseek uses python, more
Guido van Rossum <guido@python.org>
parents:
1740
diff
changeset
|
662 |
| 2048 | 663 python -- script.py [options] |
| 664 | |
| 665 Note that a working getopt implementation is provided in the Python | |
| 666 distribution (in Python/getopt.c) but not automatically used. | |
|
1541
630e03109c63
Released version 1.4; out after 1.0.0 is released...
Guido van Rossum <guido@python.org>
parents:
1535
diff
changeset
|
667 |
|
2716
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
668 3.5. Q. When building on the SGI, make tries to run python to create |
|
1541
630e03109c63
Released version 1.4; out after 1.0.0 is released...
Guido van Rossum <guido@python.org>
parents:
1535
diff
changeset
|
669 glmodule.c, but python hasn't been built or installed yet. |
|
630e03109c63
Released version 1.4; out after 1.0.0 is released...
Guido van Rossum <guido@python.org>
parents:
1535
diff
changeset
|
670 |
|
630e03109c63
Released version 1.4; out after 1.0.0 is released...
Guido van Rossum <guido@python.org>
parents:
1535
diff
changeset
|
671 A. Comment out the line mentioning glmodule.c in Setup and build a |
|
630e03109c63
Released version 1.4; out after 1.0.0 is released...
Guido van Rossum <guido@python.org>
parents:
1535
diff
changeset
|
672 python without gl first; install it or make sure it is in your $PATH, |
|
630e03109c63
Released version 1.4; out after 1.0.0 is released...
Guido van Rossum <guido@python.org>
parents:
1535
diff
changeset
|
673 then edit the Setup file again to turn on the gl module, and make |
|
630e03109c63
Released version 1.4; out after 1.0.0 is released...
Guido van Rossum <guido@python.org>
parents:
1535
diff
changeset
|
674 again. You don't need to do "make clean"; you do need to run "make |
|
630e03109c63
Released version 1.4; out after 1.0.0 is released...
Guido van Rossum <guido@python.org>
parents:
1535
diff
changeset
|
675 Makefile" in the Modules subdirectory (or just run "make" at the |
|
630e03109c63
Released version 1.4; out after 1.0.0 is released...
Guido van Rossum <guido@python.org>
parents:
1535
diff
changeset
|
676 toplevel). |
|
630e03109c63
Released version 1.4; out after 1.0.0 is released...
Guido van Rossum <guido@python.org>
parents:
1535
diff
changeset
|
677 |
|
4250
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
678 3.6. Q. I use VPATH but some targets are built in the source directory. |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
679 |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
680 A. On some systems (e.g. Sun), if the target already exists in the |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
681 source directory, it is created there instead of in the build |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
682 directory. This is usually because you have previously built without |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
683 VPATH. Try running "make clobber" in the source directory. |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
684 |
|
4250
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
685 3.7. Q. Trouble building or linking with the GNU readline library. |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
686 |
|
2660
4eb6ddb9e961
Some more changes for 1.2
Guido van Rossum <guido@python.org>
parents:
2526
diff
changeset
|
687 A. Consider using readline 2.0. Some hints: |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
688 |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
689 - You can use the GNU readline library to improve the interactive user |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
690 interface: this gives you line editing and command history when |
|
2208
c68a0113b75a
intermediate version -- why not...
Guido van Rossum <guido@python.org>
parents:
2048
diff
changeset
|
691 calling python interactively. You need to configure and build the GNU |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
692 readline library before running the configure script. Its sources are |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
693 no longer distributed with Python; you can ftp them from any GNU |
| 2048 | 694 mirror site, or from its home site |
| 695 <URL:ftp://slc2.ins.cwru.edu/pub/dist/readline-2.0.tar.gz> (or a | |
| 696 higher version number -- using version 1.x is not recommended). Pass | |
| 697 the Python configure script the option --with-readline=DIRECTORY where | |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
698 DIRECTORY is the absolute pathname of the directory where you've built |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
699 the readline library. Some hints on building and using the readline |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
700 library: |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
701 |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
702 - On SGI IRIX 5, you may have to add the following |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
703 to rldefs.h: |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
704 |
| 2048 | 705 #ifndef sigmask |
| 706 #define sigmask(sig) (1L << ((sig)-1)) | |
| 707 #endif | |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
708 |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
709 - On most systems, you will have to add #include "rldefs.h" to the |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
710 top of several source files, and if you use the VPATH feature, you |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
711 will have to add dependencies of the form foo.o: foo.c to the |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
712 Makefile for several values of foo. |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
713 |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
714 - The readline library requires use of the termcap library. A |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
715 known problem with this is that it contains entry points which |
| 1942 | 716 cause conflicts with the STDWIN and SGI GL libraries. The STDWIN |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
717 conflict can be solved (and will be, in the next release of |
| 1942 | 718 STDWIN) by adding a line saying '#define werase w_erase' to the |
| 719 stdwin.h file (in the STDWIN distribution, subdirectory H). The | |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
720 GL conflict has been solved in the Python configure script by a |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
721 hack that forces use of the static version of the termcap library. |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
722 |
|
2660
4eb6ddb9e961
Some more changes for 1.2
Guido van Rossum <guido@python.org>
parents:
2526
diff
changeset
|
723 - Check the newsgroup gnu.bash.bug <URL:news:gnu.bash.bug> for |
|
4eb6ddb9e961
Some more changes for 1.2
Guido van Rossum <guido@python.org>
parents:
2526
diff
changeset
|
724 specific problems with the readline library (I don't read this group |
|
4eb6ddb9e961
Some more changes for 1.2
Guido van Rossum <guido@python.org>
parents:
2526
diff
changeset
|
725 but I've been told that it is the place for readline bugs). |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
726 |
|
4250
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
727 3.8. Q. Trouble with socket I/O on older Linux 1.x versions. |
|
3727
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
728 |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
729 A. Once you've built Python, use it to run the regen.py script in the |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
730 Lib/linux1 directory. Apparently the files as distributed don't match |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
731 the system headers on some Linux versions. |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
732 |
|
4250
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
733 3.9. Q. Trouble with prototypes on Ultrix. |
|
1957
38dcb090f48b
add warning about ultrix cc
Guido van Rossum <guido@python.org>
parents:
1942
diff
changeset
|
734 |
|
38dcb090f48b
add warning about ultrix cc
Guido van Rossum <guido@python.org>
parents:
1942
diff
changeset
|
735 A. Ultrix cc seems broken -- use gcc, or edit config.h to #undef |
|
38dcb090f48b
add warning about ultrix cc
Guido van Rossum <guido@python.org>
parents:
1942
diff
changeset
|
736 HAVE_PROTOTYPES. |
|
38dcb090f48b
add warning about ultrix cc
Guido van Rossum <guido@python.org>
parents:
1942
diff
changeset
|
737 |
|
4376
d4f64fc42d84
Toss Q 3.10 on posix.listdir on NeXT. Add revived vpApp.
Guido van Rossum <guido@python.org>
parents:
4278
diff
changeset
|
738 3.10. Q. Other trouble building Python on platform X. |
|
1533
995a8ef4a5c0
Changes for release of 1.0.0
Guido van Rossum <guido@python.org>
parents:
1529
diff
changeset
|
739 |
|
4221
66913ca7ec47
New email and zip code for Guido
Guido van Rossum <guido@python.org>
parents:
3865
diff
changeset
|
740 A. Please email the details to <guido@cnri.reston.va.us> and I'll look |
|
66913ca7ec47
New email and zip code for Guido
Guido van Rossum <guido@python.org>
parents:
3865
diff
changeset
|
741 into it. Please provide as many details as possible. In particular, |
|
66913ca7ec47
New email and zip code for Guido
Guido van Rossum <guido@python.org>
parents:
3865
diff
changeset
|
742 if you don't tell me what type of computer and what operating system |
|
66913ca7ec47
New email and zip code for Guido
Guido van Rossum <guido@python.org>
parents:
3865
diff
changeset
|
743 (and version) you are using it will be difficult for me to figure out |
|
66913ca7ec47
New email and zip code for Guido
Guido van Rossum <guido@python.org>
parents:
3865
diff
changeset
|
744 what is the matter. If you get a specific error message, please email |
|
66913ca7ec47
New email and zip code for Guido
Guido van Rossum <guido@python.org>
parents:
3865
diff
changeset
|
745 it to me too. |
| 1529 | 746 |
|
4376
d4f64fc42d84
Toss Q 3.10 on posix.listdir on NeXT. Add revived vpApp.
Guido van Rossum <guido@python.org>
parents:
4278
diff
changeset
|
747 3.11. Q. How to configure dynamic loading on Linux. |
|
4250
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
748 |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
749 A. This is now automatic as long as your Linux version uses the ELF |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
750 object format (all recent Linuxes do). |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
751 |
|
4408
6c771ea38eee
Added item about bug in Slackware96 libdl.
Guido van Rossum <guido@python.org>
parents:
4376
diff
changeset
|
752 3.12. Q: I can't get shared modules to work on Linux 2.0 (Slackware96)? |
|
6c771ea38eee
Added item about bug in Slackware96 libdl.
Guido van Rossum <guido@python.org>
parents:
4376
diff
changeset
|
753 |
|
6c771ea38eee
Added item about bug in Slackware96 libdl.
Guido van Rossum <guido@python.org>
parents:
4376
diff
changeset
|
754 A: This is a bug in the Slackware96 release. The fix is simple: |
|
6c771ea38eee
Added item about bug in Slackware96 libdl.
Guido van Rossum <guido@python.org>
parents:
4376
diff
changeset
|
755 |
|
6c771ea38eee
Added item about bug in Slackware96 libdl.
Guido van Rossum <guido@python.org>
parents:
4376
diff
changeset
|
756 Make sure that there is a link from /lib/libdl.so to /lib/libdl.so.1 |
|
6c771ea38eee
Added item about bug in Slackware96 libdl.
Guido van Rossum <guido@python.org>
parents:
4376
diff
changeset
|
757 so that the following links are setup: |
|
6c771ea38eee
Added item about bug in Slackware96 libdl.
Guido van Rossum <guido@python.org>
parents:
4376
diff
changeset
|
758 |
|
6c771ea38eee
Added item about bug in Slackware96 libdl.
Guido van Rossum <guido@python.org>
parents:
4376
diff
changeset
|
759 /lib/libdl.so -> /lib/libdl.so.1 |
|
6c771ea38eee
Added item about bug in Slackware96 libdl.
Guido van Rossum <guido@python.org>
parents:
4376
diff
changeset
|
760 /lib/libdl.so.1 -> /lib/libdl.so.1.7.14 |
|
6c771ea38eee
Added item about bug in Slackware96 libdl.
Guido van Rossum <guido@python.org>
parents:
4376
diff
changeset
|
761 |
| 5126 | 762 You may have to rerun the configure script, after rm'ing the |
| 763 config.cache file, before you attempt to rebuild python after this | |
| 764 fix. | |
| 765 | |
|
4542
652303ef926b
Added Q. about enabling *shared* on Linux.
Guido van Rossum <guido@python.org>
parents:
4480
diff
changeset
|
766 3.13. Q: Trouble when making modules shared on Linux. |
|
652303ef926b
Added Q. about enabling *shared* on Linux.
Guido van Rossum <guido@python.org>
parents:
4480
diff
changeset
|
767 |
|
652303ef926b
Added Q. about enabling *shared* on Linux.
Guido van Rossum <guido@python.org>
parents:
4480
diff
changeset
|
768 A. This happens when you have built Python for static linking and then |
|
652303ef926b
Added Q. about enabling *shared* on Linux.
Guido van Rossum <guido@python.org>
parents:
4480
diff
changeset
|
769 enable *shared* in the Setup file. Shared library code must be |
|
652303ef926b
Added Q. about enabling *shared* on Linux.
Guido van Rossum <guido@python.org>
parents:
4480
diff
changeset
|
770 compiled with "-fpic". If a .o file for the module already exist that |
|
652303ef926b
Added Q. about enabling *shared* on Linux.
Guido van Rossum <guido@python.org>
parents:
4480
diff
changeset
|
771 was compiled for static linking, you must remove it or do "make clean" |
|
652303ef926b
Added Q. about enabling *shared* on Linux.
Guido van Rossum <guido@python.org>
parents:
4480
diff
changeset
|
772 in the Modules directory. |
|
652303ef926b
Added Q. about enabling *shared* on Linux.
Guido van Rossum <guido@python.org>
parents:
4480
diff
changeset
|
773 |
|
652303ef926b
Added Q. about enabling *shared* on Linux.
Guido van Rossum <guido@python.org>
parents:
4480
diff
changeset
|
774 3.14. Q. How to use threads on Linux. |
|
4480
9e853a5f04ff
Added answer by Greg Stein about threads on Linux.
Guido van Rossum <guido@python.org>
parents:
4438
diff
changeset
|
775 |
|
9e853a5f04ff
Added answer by Greg Stein about threads on Linux.
Guido van Rossum <guido@python.org>
parents:
4438
diff
changeset
|
776 A. [Greg Stein] I built myself a libpthreads.so from the libc.5.3.12 |
|
9e853a5f04ff
Added answer by Greg Stein about threads on Linux.
Guido van Rossum <guido@python.org>
parents:
4438
diff
changeset
|
777 distribution (the binary distribution doesn't have pthreads in |
|
9e853a5f04ff
Added answer by Greg Stein about threads on Linux.
Guido van Rossum <guido@python.org>
parents:
4438
diff
changeset
|
778 it). Then, I configured Python with --with-threads and then tweaked |
|
9e853a5f04ff
Added answer by Greg Stein about threads on Linux.
Guido van Rossum <guido@python.org>
parents:
4438
diff
changeset
|
779 config.h to include a #define _MIT_POSIX_THREADS (or something like |
|
9e853a5f04ff
Added answer by Greg Stein about threads on Linux.
Guido van Rossum <guido@python.org>
parents:
4438
diff
changeset
|
780 that, see /usr/include/pthreads.h). It worked fine at that point. |
|
9e853a5f04ff
Added answer by Greg Stein about threads on Linux.
Guido van Rossum <guido@python.org>
parents:
4438
diff
changeset
|
781 |
|
9e853a5f04ff
Added answer by Greg Stein about threads on Linux.
Guido van Rossum <guido@python.org>
parents:
4438
diff
changeset
|
782 Note that I couldn't get threading to "operate well" with any of the |
|
9e853a5f04ff
Added answer by Greg Stein about threads on Linux.
Guido van Rossum <guido@python.org>
parents:
4438
diff
changeset
|
783 other thread packages. Prior libc versions didn't integrate well with |
|
9e853a5f04ff
Added answer by Greg Stein about threads on Linux.
Guido van Rossum <guido@python.org>
parents:
4438
diff
changeset
|
784 threads, either, so I couldn't use them (e.g. sleep() blocked all |
|
9e853a5f04ff
Added answer by Greg Stein about threads on Linux.
Guido van Rossum <guido@python.org>
parents:
4438
diff
changeset
|
785 threads :-( ). |
|
9e853a5f04ff
Added answer by Greg Stein about threads on Linux.
Guido van Rossum <guido@python.org>
parents:
4438
diff
changeset
|
786 |
|
4542
652303ef926b
Added Q. about enabling *shared* on Linux.
Guido van Rossum <guido@python.org>
parents:
4480
diff
changeset
|
787 3.15. Q. Errors when linking with a shared library containing C++ code. |
| 2855 | 788 |
| 789 A. Link the main Python binary with C++. Change the definition of | |
| 790 LINKCC in Modules/Makefile to be your C++ compiler. You may have to | |
| 791 edit config.c slightly to make it compilable with C++. | |
| 2301 | 792 |
|
4542
652303ef926b
Added Q. about enabling *shared* on Linux.
Guido van Rossum <guido@python.org>
parents:
4480
diff
changeset
|
793 3.16. Q. I built with tkintermodule.c enabled but get "Tkinter not found". |
|
3023
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
794 |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
795 A. Tkinter.py (note: upper case T) lives in a subdirectory of Lib, |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
796 Lib/tkinter. If you are using the default module search path, you |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
797 probably didn't enable the line in the Modules/Setup file defining |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
798 TKPATH; if you use the environment variable PYTHONPATH, you'll have to |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
799 add the proper tkinter subdirectory. |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
800 |
|
4542
652303ef926b
Added Q. about enabling *shared* on Linux.
Guido van Rossum <guido@python.org>
parents:
4480
diff
changeset
|
801 3.17. Q. I built with Tk 4.0 but Tkinter complains about the Tk version. |
|
3023
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
802 |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
803 A. Several things could cause this. You most likely have a Tk 3.6 |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
804 installation that wasn't completely eradicated by the Tk 4.0 |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
805 installation (which tends to add "4.0" to its installed files). You |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
806 may have the Tk 3.6 support library installed in the place where the |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
807 Tk 4.0 support files should be (default /usr/local/lib/tk/); you may |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
808 have compiled Python with the old tk.h header file (yes, this actually |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
809 compiles!); you may actually have linked with Tk 3.6 even though Tk |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
810 4.0 is also around. Similar for Tcl 7.4 vs. Tcl 7.3. |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
811 |
|
4542
652303ef926b
Added Q. about enabling *shared* on Linux.
Guido van Rossum <guido@python.org>
parents:
4480
diff
changeset
|
812 3.18. Q. Link errors for Tcl/Tk symbols when linking with Tcl/Tk. |
|
4250
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
813 |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
814 Quite possibly, there's a version mismatch between the Tcl/Tk header |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
815 files (tcl.h and tk.h) and the tck/tk libraries you are using (the |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
816 "-ltk4.0" and "-ltcl7.4" arguments for _tkinter in the Setup file). |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
817 If you have installed both versions 7.4/4.0 and 7.5/4.1 of Tcl/Tk, |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
818 most likely your header files are for The newer versions, but the |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
819 Setup line for _tkinter in some Python distributions references |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
820 7.4/4.0 by default. Changing this to 7.5/4.1 should take care of |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
821 this. |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
822 |
|
4542
652303ef926b
Added Q. about enabling *shared* on Linux.
Guido van Rossum <guido@python.org>
parents:
4480
diff
changeset
|
823 3.19. Q. I configured and built Python for Tcl/Tk but "import Tkinter" |
|
4250
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
824 fails. |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
825 |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
826 A. Most likely, you forgot to enable the line in Setup that says |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
827 "TKPATH=:$(DESTLIB)/tkinter". |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
828 |
|
4542
652303ef926b
Added Q. about enabling *shared* on Linux.
Guido van Rossum <guido@python.org>
parents:
4480
diff
changeset
|
829 3.20. Q. Tk doesn't work right on DEC Alpha. |
|
3023
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
830 |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
831 A. You probably compiled either Tcl, Tk or Python with gcc. Don't. |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
832 For this platform, which has 64-bit integers, gcc is known to generate |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
833 broken code. The standard cc (which comes bundled with the OS!) |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
834 works. If you still prefer gcc, at least try recompiling with cc |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
835 before reporting problems to the newsgroup or the author; if this |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
836 fixes the problem, report the bug to the gcc developers instead. (As |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
837 far as we know, there are no problem with gcc on other platforms -- |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
838 the instabilities seem to be restricted to the DEC Alpha.) See also |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
839 question 3.6. |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
840 |
|
4542
652303ef926b
Added Q. about enabling *shared* on Linux.
Guido van Rossum <guido@python.org>
parents:
4480
diff
changeset
|
841 3.21. Q. Several common system calls are missing from the posix module. |
|
3727
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
842 |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
843 A. Most likely, *all* test compilations run by the configure script |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
844 are failing for some reason or another. Have a look in config.log to |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
845 see what could be the reason. A common reason is specifying a |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
846 directory to the --with-readline option that doesn't contain the |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
847 libreadline.a file. |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
848 |
|
4542
652303ef926b
Added Q. about enabling *shared* on Linux.
Guido van Rossum <guido@python.org>
parents:
4480
diff
changeset
|
849 3.22. Q. ImportError: No module named string, on MS Windows. |
|
3727
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
850 |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
851 A. Most likely, your PYTHONPATH environment variable should be set to |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
852 something like: |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
853 |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
854 set PYTHONPATH=c:\python;c:\python\lib;c:\python\scripts |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
855 |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
856 (assuming Python was installed in c:\python) |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
857 |
|
4542
652303ef926b
Added Q. about enabling *shared* on Linux.
Guido van Rossum <guido@python.org>
parents:
4480
diff
changeset
|
858 3.23. Q. Core dump on SGI when using the gl module. |
|
3727
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
859 |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
860 There are conflicts between entry points in the termcap and curses |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
861 libraries and an entry point in the GL library. There's a hack of a |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
862 fix for the termcap library if it's needed for the GNU readline |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
863 library, but it doesn't work when you're using curses. Concluding, |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
864 you can't build a Python binary containing both the curses and gl |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
865 modules. |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
866 |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
867 |
| 1529 | 868 |
| 869 4. Programming in Python | |
| 870 ======================== | |
| 871 | |
|
1541
630e03109c63
Released version 1.4; out after 1.0.0 is released...
Guido van Rossum <guido@python.org>
parents:
1535
diff
changeset
|
872 4.1. Q. Is there a source code level debugger with breakpoints, step, |
|
630e03109c63
Released version 1.4; out after 1.0.0 is released...
Guido van Rossum <guido@python.org>
parents:
1535
diff
changeset
|
873 etc.? |
|
630e03109c63
Released version 1.4; out after 1.0.0 is released...
Guido van Rossum <guido@python.org>
parents:
1535
diff
changeset
|
874 |
|
630e03109c63
Released version 1.4; out after 1.0.0 is released...
Guido van Rossum <guido@python.org>
parents:
1535
diff
changeset
|
875 A. Yes. Check out module pdb; pdb.help() prints the documentation (or |
|
630e03109c63
Released version 1.4; out after 1.0.0 is released...
Guido van Rossum <guido@python.org>
parents:
1535
diff
changeset
|
876 you can read it as Lib/pdb.doc). If you use the STDWIN option, |
|
630e03109c63
Released version 1.4; out after 1.0.0 is released...
Guido van Rossum <guido@python.org>
parents:
1535
diff
changeset
|
877 there's also a windowing interface, wdb. You can write your own |
|
630e03109c63
Released version 1.4; out after 1.0.0 is released...
Guido van Rossum <guido@python.org>
parents:
1535
diff
changeset
|
878 debugger by using the code for pdb or wdb as an example. |
|
630e03109c63
Released version 1.4; out after 1.0.0 is released...
Guido van Rossum <guido@python.org>
parents:
1535
diff
changeset
|
879 |
|
630e03109c63
Released version 1.4; out after 1.0.0 is released...
Guido van Rossum <guido@python.org>
parents:
1535
diff
changeset
|
880 4.2. Q. Can I create an object class with some methods implemented in |
| 1529 | 881 C and others in Python (e.g. through inheritance)? (Also phrased as: |
| 882 Can I use a built-in type as base class?) | |
| 883 | |
| 884 A. No, but you can easily create a Python class which serves as a | |
| 885 wrapper around a built-in object, e.g. (for dictionaries): | |
| 886 | |
| 2048 | 887 # A user-defined class behaving almost identical |
| 888 # to a built-in dictionary. | |
| 889 class UserDict: | |
| 890 def __init__(self): self.data = {} | |
| 891 def __repr__(self): return repr(self.data) | |
| 892 def __cmp__(self, dict): | |
| 893 if type(dict) == type(self.data): | |
| 894 return cmp(self.data, dict) | |
| 895 else: | |
| 896 return cmp(self.data, dict.data) | |
| 897 def __len__(self): return len(self.data) | |
| 898 def __getitem__(self, key): return self.data[key] | |
| 899 def __setitem__(self, key, item): self.data[key] = item | |
| 900 def __delitem__(self, key): del self.data[key] | |
| 901 def keys(self): return self.data.keys() | |
| 902 def items(self): return self.data.items() | |
| 903 def values(self): return self.data.values() | |
| 904 def has_key(self, key): return self.data.has_key(key) | |
| 1529 | 905 |
| 5126 | 906 A2. See Jim Fulton's ExtensionClass for an example of a mechanism |
| 907 which allows you to have superclasses which you can inherit from in | |
| 908 Python -- that way you can have some methods from a C superclass (call | |
| 909 it a mixin) and some methods from either a Python superclass or your | |
| 910 subclass. See <URL:http://www.digicool.com/papers/ExtensionClass.html>. | |
| 911 | |
|
1541
630e03109c63
Released version 1.4; out after 1.0.0 is released...
Guido van Rossum <guido@python.org>
parents:
1535
diff
changeset
|
912 4.3. Q. Is there a curses/termcap package for Python? |
| 1529 | 913 |
| 2048 | 914 A. Yes -- Lance Ellinghaus has written a module that interfaces to |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
915 System V's "ncurses". If you know a little curses and some Python, |
| 2048 | 916 it's straightforward to use. It is part of the standard Python |
| 917 distribution, but not configured by default -- you must enable it by | |
| 918 editing Modules/Setup. It requires a System V curses implementation. | |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
919 |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
920 You could also consider using the "alfa" (== character cell) version |
| 2048 | 921 of STDWIN. (Standard Window System Interface, a portable windowing |
| 922 system interface by myself <URL:ftp://ftp.cwi.nl/pub/stdwin/>.) This | |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
923 will also prepare your program for porting to windowing environments |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
924 such as X11 or the Macintosh. |
| 1529 | 925 |
|
1541
630e03109c63
Released version 1.4; out after 1.0.0 is released...
Guido van Rossum <guido@python.org>
parents:
1535
diff
changeset
|
926 4.4. Q. Is there an equivalent to C's onexit() in Python? |
| 1529 | 927 |
| 928 A. Yes, if you import sys and assign a function to sys.exitfunc, it | |
| 929 will be called when your program exits, is killed by an unhandled | |
| 930 exception, or (on UNIX) receives a SIGHUP or SIGTERM signal. | |
| 931 | |
|
1541
630e03109c63
Released version 1.4; out after 1.0.0 is released...
Guido van Rossum <guido@python.org>
parents:
1535
diff
changeset
|
932 4.5. Q. When I define a function nested inside another function, the |
| 1529 | 933 nested function seemingly can't access the local variables of the |
| 934 outer function. What is going on? How do I pass local data to a | |
| 935 nested function? | |
| 936 | |
| 937 A. Python does not have arbitrarily nested scopes. When you need to | |
| 938 create a function that needs to access some data which you have | |
| 939 available locally, create a new class to hold the data and return a | |
| 940 method of an instance of that class, e.g.: | |
| 941 | |
| 2048 | 942 class MultiplierClass: |
| 943 def __init__(self, factor): | |
| 944 self.factor = factor | |
| 945 def multiplier(self, argument): | |
| 946 return argument * self.factor | |
| 947 | |
| 948 def generate_multiplier(factor): | |
| 949 return MultiplierClass(factor).multiplier | |
| 1529 | 950 |
| 2048 | 951 twice = generate_multiplier(2) |
| 952 print twice(10) | |
| 953 # Output: 20 | |
| 954 | |
| 955 An alternative solution uses default arguments, e.g.: | |
| 1529 | 956 |
| 2048 | 957 def generate_multiplier(factor): |
| 958 def multiplier(arg, fact = factor): | |
| 959 return arg*fact | |
| 960 return multiplier | |
| 961 | |
| 962 twice = generate_multiplier(2) | |
| 963 print twice(10) | |
| 964 # Output: 20 | |
| 1529 | 965 |
|
1541
630e03109c63
Released version 1.4; out after 1.0.0 is released...
Guido van Rossum <guido@python.org>
parents:
1535
diff
changeset
|
966 4.6. Q. How do I iterate over a sequence in reverse order? |
| 1529 | 967 |
| 968 A. If it is a list, the fastest solution is | |
| 969 | |
| 2048 | 970 list.reverse() |
| 971 try: | |
| 972 for x in list: | |
| 973 "do something with x" | |
| 974 finally: | |
| 975 list.reverse() | |
| 1529 | 976 |
| 977 This has the disadvantage that while you are in the loop, the list | |
| 978 is temporarily reversed. If you don't like this, you can make a copy. | |
| 979 This appears expensive but is actually faster than other solutions: | |
| 980 | |
| 2048 | 981 rev = list[:] |
| 982 rev.reverse() | |
| 983 for x in rev: | |
| 984 <do something with x> | |
| 1529 | 985 |
| 986 If it isn't a list, a more general but slower solution is: | |
| 987 | |
| 2048 | 988 i = len(list) |
| 989 while i > 0: | |
| 990 i = i-1 | |
| 991 x = list[i] | |
| 992 <do something with x> | |
| 1529 | 993 |
| 994 A more elegant solution, is to define a class which acts as a sequence | |
| 995 and yields the elements in reverse order (solution due to Steve | |
| 996 Majewski): | |
| 997 | |
| 2048 | 998 class Rev: |
| 999 def __init__(self, seq): | |
| 1000 self.forw = seq | |
| 1001 def __len__(self): | |
| 1002 return len(self.forw) | |
| 1003 def __getitem__(self, i): | |
| 1004 return self.forw[-(i + 1)] | |
| 1529 | 1005 |
| 1006 You can now simply write: | |
| 1007 | |
| 2048 | 1008 for x in Rev(list): |
| 1009 <do something with x> | |
| 1529 | 1010 |
| 1942 | 1011 Unfortunately, this solution is slowest of all, due to the method |
| 1529 | 1012 call overhead... |
| 1013 | |
|
1541
630e03109c63
Released version 1.4; out after 1.0.0 is released...
Guido van Rossum <guido@python.org>
parents:
1535
diff
changeset
|
1014 4.7. Q. My program is too slow. How do I speed it up? |
| 1529 | 1015 |
| 1016 A. That's a tough one, in general. There are many tricks to speed up | |
| 1017 Python code; I would consider rewriting parts in C only as a last | |
| 1018 resort. One thing to notice is that function and (especially) method | |
| 1019 calls are rather expensive; if you have designed a purely OO interface | |
| 1020 with lots of tiny functions that don't do much more than get or set an | |
| 1021 instance variable or call another method, you may consider using a | |
| 1022 more direct way, e.g. directly accessing instance variables. Also see | |
| 1023 the standard module "profile" (described in the file | |
| 1024 "python/lib/profile.doc") which makes it possible to find out where | |
| 1025 your program is spending most of its time (if you have some patience | |
| 1026 -- the profiling itself can slow your program down by an order of | |
| 1027 magnitude). | |
| 1028 | |
|
1541
630e03109c63
Released version 1.4; out after 1.0.0 is released...
Guido van Rossum <guido@python.org>
parents:
1535
diff
changeset
|
1029 4.8. Q. When I have imported a module, then edit it, and import it |
| 1529 | 1030 again (into the same Python process), the changes don't seem to take |
| 1031 place. What is going on? | |
| 1032 | |
| 2048 | 1033 A. For reasons of efficiency as well as consistency, Python only reads |
|
2208
c68a0113b75a
intermediate version -- why not...
Guido van Rossum <guido@python.org>
parents:
2048
diff
changeset
|
1034 the module file on the first time a module is imported. (Otherwise a |
| 2048 | 1035 program consisting of many modules, each of which imports the same |
|
2208
c68a0113b75a
intermediate version -- why not...
Guido van Rossum <guido@python.org>
parents:
2048
diff
changeset
|
1036 basic module, would read the basic module over and over again.) To |
|
c68a0113b75a
intermediate version -- why not...
Guido van Rossum <guido@python.org>
parents:
2048
diff
changeset
|
1037 force rereading of a changed module, do this: |
| 1529 | 1038 |
| 2048 | 1039 import modname |
| 1040 reload(modname) | |
| 1529 | 1041 |
| 1042 Warning: this technique is not 100% fool-proof. In particular, | |
| 1043 modules containing statements like | |
| 1044 | |
| 2048 | 1045 from modname import some_objects |
| 1529 | 1046 |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1047 will continue to work with the old version of the imported objects. |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1048 |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1049 4.9. Q. How do I find the current module name? |
| 1529 | 1050 |
| 1942 | 1051 A. A module can find out its own module name by looking at the |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1052 (predefined) global variable __name__. If this has the value |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1053 '__main__' you are running as a script. |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1054 |
| 2048 | 1055 4.10. Q. I have a module in which I want to execute some extra code |
| 1056 when it is run as a script. How do I find out whether I am running as | |
| 1057 a script? | |
|
1541
630e03109c63
Released version 1.4; out after 1.0.0 is released...
Guido van Rossum <guido@python.org>
parents:
1535
diff
changeset
|
1058 |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1059 A. See the previous question. E.g. if you put the following on the |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1060 last line of your module, main() is called only when your module is |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1061 running as a script: |
|
1541
630e03109c63
Released version 1.4; out after 1.0.0 is released...
Guido van Rossum <guido@python.org>
parents:
1535
diff
changeset
|
1062 |
| 2048 | 1063 if __name__ == '__main__': main() |
|
1541
630e03109c63
Released version 1.4; out after 1.0.0 is released...
Guido van Rossum <guido@python.org>
parents:
1535
diff
changeset
|
1064 |
| 2048 | 1065 4.11. Q. I try to run a program from the Demo directory but it fails |
| 1066 with ImportError: No module named ...; what gives? | |
| 1663 | 1067 |
| 1942 | 1068 A. This is probably an optional module (written in C!) which hasn't |
| 1069 been configured on your system. This especially happens with modules | |
| 2048 | 1070 like "Tkinter", "stdwin", "gl", "Xt" or "Xm". For Tkinter, STDWIN and |
| 1071 many other modules, see Modules/Setup.in for info on how to add these | |
| 1072 modules to your Python, if it is possible at all. Sometimes you will | |
| 1073 have to ftp and build another package first (e.g. STDWIN). Sometimes | |
| 1074 the module only works on specific platforms (e.g. gl only works on SGI | |
| 1075 machines). | |
| 1076 | |
| 1077 NOTE: if the complaint is about "Tkinter" (upper case T) and you have | |
|
3727
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1078 already configured module "tkinter" (lower case t), the solution is |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1079 *not* to rename tkinter to Tkinter or vice versa. There is probably |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1080 something wrong with your module search path. Check out the value of |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1081 sys.path. |
| 1663 | 1082 |
| 1942 | 1083 For X-related modules (Xt and Xm) you will have to do more work: they |
| 1084 are currently not part of the standard Python distribution. You will | |
| 2048 | 1085 have to ftp the Extensions tar file, e.g. |
|
2716
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
1086 <URL:ftp://ftp.python.org/pub/python/src/extensions.tar.gz> and follow |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
1087 the instructions there. |
| 1942 | 1088 |
| 1089 See also the next question. | |
| 1090 | |
| 1091 4.12. Q. I have successfully built Python with STDWIN but it can't | |
| 1092 find some modules (e.g. stdwinevents). | |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1093 |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1094 A. There's a subdirectory of the library directory named 'stdwin' |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1095 which should be in the default module search path. There's a line in |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1096 Modules/Setup(.in) that you have to enable for this purpose -- |
| 1942 | 1097 unfortunately in the latest release it's not near the other |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1098 STDWIN-related lines so it's easy to miss it. |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1099 |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1100 4.13. Q. What GUI toolkits exist for Python? |
| 1663 | 1101 |
| 1102 A. Depending on what platform(s) you are aiming at, there are several. | |
| 1103 | |
|
4278
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1104 Currently supported solutions: |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1105 |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1106 - There's a neat object-oriented interface to the Tcl/Tk widget set, |
|
4278
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1107 called Tkinter. It is part of the standard Python distribution and |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1108 well-supported -- all you need to do is build and install Tcl/Tk and |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1109 enable the _tkinter module and the TKPATH definition in Modules/Setup |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1110 when building Python. This is probably the easiest to install and |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1111 use, and the most complete widget set. It is also very likely that in |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1112 the future the standard Python GUI API will be based on or at least |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1113 look very much like the Tkinter interface. For more info about Tk, |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1114 including pointers to the source, see the Tcl/Tk home page |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1115 <URL:http://www.sunlabs.com/research/tcl/>. Tcl/Tk is now fully |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1116 portable to the Mac and Windows platforms (NT and 95 only); you need |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1117 Python 1.4beta3 or later and Tk 4.1patch1 or later. |
| 1663 | 1118 |
| 1119 - There's an interface to X11, including the Athena and Motif widget | |
| 1120 sets (and a few individual widgets, like Mosaic's HTML widget and | |
|
4278
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1121 SGI's GL widget) available from |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1122 <URL:ftp://ftp.python.org/pub/python/src/X-extension.tar.gz>. |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1123 Support by Sjoerd Mullender <sjoerd@cwi.nl>. |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1124 |
|
4376
d4f64fc42d84
Toss Q 3.10 on posix.listdir on NeXT. Add revived vpApp.
Guido van Rossum <guido@python.org>
parents:
4278
diff
changeset
|
1125 - On top of the X11 interface there's the (recently revived) vpApp |
|
d4f64fc42d84
Toss Q 3.10 on posix.listdir on NeXT. Add revived vpApp.
Guido van Rossum <guido@python.org>
parents:
4278
diff
changeset
|
1126 toolkit by Per Spilling, now also maintained by Sjoerd Mullender |
|
d4f64fc42d84
Toss Q 3.10 on posix.listdir on NeXT. Add revived vpApp.
Guido van Rossum <guido@python.org>
parents:
4278
diff
changeset
|
1127 <sjoerd@cwi.nl>. See <URL:ftp://ftp.cwi.nl/pub/sjoerd/vpApp.tar.gz>. |
|
d4f64fc42d84
Toss Q 3.10 on posix.listdir on NeXT. Add revived vpApp.
Guido van Rossum <guido@python.org>
parents:
4278
diff
changeset
|
1128 |
|
4278
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1129 - The Mac port has a rich and ever-growing set of modules that support |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1130 the native Mac toolbox calls. See the documentation that comes with |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1131 the Mac port. See <URL:ftp://ftp.python.org/pub/python/mac>. Support |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1132 by Jack Jansen <jack@cwi.nl>. |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1133 |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1134 - The NT port supported by Mark Hammond <MHammond@skippinet.com.au> |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1135 (see question 7.2) includes an interface to the Microsoft Foundation |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1136 Classes and a Python programming environment using it that's written |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1137 mostly in Python. See |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1138 <URL:ftp://ftp.python.org/pub/python/pythonwin/>. |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1139 |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1140 - There's an object-oriented GUI based on the Microsoft Foundation |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1141 Classes model called WPY, supported by Jim Ahlstrom <jim@interet.com>. |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1142 Programs written in WPY run unchanged and with native look and feel on |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1143 Windows NT/95, Windows 3.1 (using win32s), and on Unix (using Tk). |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1144 Source and binaries for Windows and Linux are available in |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1145 <URL:ftp://ftp.python.org/pub/python/wpy/>. |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1146 |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1147 Obsolete or minority solutions: |
| 3018 | 1148 |
|
2526
d1123b10cf23
removed GPL mumbo jumbo
Guido van Rossum <guido@python.org>
parents:
2301
diff
changeset
|
1149 - There's an interface to wxWindows. wxWindows is a portable GUI |
|
d1123b10cf23
removed GPL mumbo jumbo
Guido van Rossum <guido@python.org>
parents:
2301
diff
changeset
|
1150 class library written in C++. It supports XView, Motif, MS-Windows as |
|
4278
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1151 targets. There is some support for Macs and CURSES as well. |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1152 wxWindows preserves the look and feel of the underlying graphics |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1153 toolkit. See the wxPython WWW page at |
|
2526
d1123b10cf23
removed GPL mumbo jumbo
Guido van Rossum <guido@python.org>
parents:
2301
diff
changeset
|
1154 <URL:http://www.aiai.ed.ac.uk/~jacs/wx/wxpython/wxpython.html>. |
|
4278
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1155 Support for wxPython (by Harri Pasanen <pa@tekla.fi>) appears |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1156 to have a low priority. |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1157 |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1158 - For SGI IRIX only, there are unsupported interfaces to the complete |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1159 GL (Graphics Library -- low level but very good 3D capabilities) as |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1160 well as to FORMS (a buttons-and-sliders-etc package built on top of GL |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1161 by Mark Overmars -- ftp'able from |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1162 <URL:ftp://ftp.cs.ruu.nl/pub/SGI/FORMS/>). This is probably also |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1163 becoming obsolete, as OpenGL takes over. |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1164 |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1165 - There's an interface to STDWIN, a platform-independent low-level |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1166 windowing interface for Mac and X11. This is totally unsupported and |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1167 rapidly becoming obsolete. The STDWIN sources are at |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1168 <URL:ftp://ftp.cwi.nl/pub/stdwin/>. (For info about STDWIN 2.0, |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1169 please refer to Steven Pemberton <steven@cwi.nl> -- I believe it is |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1170 also dead.) |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1171 |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1172 - There once was an interface to WAFE, a Tcl interface to the X11 |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1173 Motif and Athena widget sets. WAFE is at |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1174 <URL:ftp://ftp.wu-wien.ac.at/pub/src/X11/wafe/>. It's not clear what |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1175 the status of the Python support is. |
| 2855 | 1176 |
|
3865
4591035228a7
Added two new questions; about globals/locals and about recursive imports.
Guido van Rossum <guido@python.org>
parents:
3727
diff
changeset
|
1177 - (The Fresco port that was mentioned in earlier versions of this FAQ |
|
4591035228a7
Added two new questions; about globals/locals and about recursive imports.
Guido van Rossum <guido@python.org>
parents:
3727
diff
changeset
|
1178 no longer seems to exist. Inquire with Mark Linton.) |
|
2526
d1123b10cf23
removed GPL mumbo jumbo
Guido van Rossum <guido@python.org>
parents:
2301
diff
changeset
|
1179 |
| 1942 | 1180 4.14. Q. Are there any interfaces to database packages in Python? |
| 1663 | 1181 |
|
4250
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
1182 A. There's a whole collection of them in the contrib area of the ftp |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
1183 server, see <URL:http://www.python.org/ftp/python/contrib/Database/>. |
|
2208
c68a0113b75a
intermediate version -- why not...
Guido van Rossum <guido@python.org>
parents:
2048
diff
changeset
|
1184 |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1185 4.15. Q. Is it possible to write obfuscated one-liners in Python? |
|
1902
53d17c04b42f
Added obfuxcated lambda's by Ulf Bertelt
Guido van Rossum <guido@python.org>
parents:
1784
diff
changeset
|
1186 |
|
53d17c04b42f
Added obfuxcated lambda's by Ulf Bertelt
Guido van Rossum <guido@python.org>
parents:
1784
diff
changeset
|
1187 A. Yes. See the following three examples, due to Ulf Bartelt: |
|
53d17c04b42f
Added obfuxcated lambda's by Ulf Bertelt
Guido van Rossum <guido@python.org>
parents:
1784
diff
changeset
|
1188 |
| 2048 | 1189 # Primes < 1000 |
| 1190 print filter(None,map(lambda y:y*reduce(lambda x,y:x*y!=0, | |
| 1191 map(lambda x,y=y:y%x,range(2,int(pow(y,0.5)+1))),1),range(2,1000))) | |
|
1902
53d17c04b42f
Added obfuxcated lambda's by Ulf Bertelt
Guido van Rossum <guido@python.org>
parents:
1784
diff
changeset
|
1192 |
| 2048 | 1193 # First 10 Fibonacci numbers |
| 1194 print map(lambda x,f=lambda x,f:(x<=1) or (f(x-1,f)+f(x-2,f)): f(x,f), | |
| 1195 range(10)) | |
|
1902
53d17c04b42f
Added obfuxcated lambda's by Ulf Bertelt
Guido van Rossum <guido@python.org>
parents:
1784
diff
changeset
|
1196 |
| 2048 | 1197 # Mandelbrot set |
| 1198 print (lambda Ru,Ro,Iu,Io,IM,Sx,Sy:reduce(lambda x,y:x+y,map(lambda y, | |
| 1199 Iu=Iu,Io=Io,Ru=Ru,Ro=Ro,Sy=Sy,L=lambda yc,Iu=Iu,Io=Io,Ru=Ru,Ro=Ro,i=IM, | |
| 1200 Sx=Sx,Sy=Sy:reduce(lambda x,y:x+y,map(lambda x,xc=Ru,yc=yc,Ru=Ru,Ro=Ro, | |
| 1201 i=i,Sx=Sx,F=lambda xc,yc,x,y,k,f=lambda xc,yc,x,y,k,f:(k<=0)or (x*x+y*y | |
| 1202 >=4.0) or 1+f(xc,yc,x*x-y*y+xc,2.0*x*y+yc,k-1,f):f(xc,yc,x,y,k,f):chr( | |
| 1203 64+F(Ru+x*(Ro-Ru)/Sx,yc,0,0,i)),range(Sx))):L(Iu+y*(Io-Iu)/Sy),range(Sy | |
| 1204 ))))(-2.1, 0.7, -1.2, 1.2, 30, 80, 24) | |
| 1205 # \___ ___/ \___ ___/ | | |__ lines on screen | |
| 1206 # V V | |______ columns on screen | |
| 1207 # | | |__________ maximum of "iterations" | |
| 1208 # | |_________________ range on y axis | |
| 1209 # |____________________________ range on x axis | |
|
1902
53d17c04b42f
Added obfuxcated lambda's by Ulf Bertelt
Guido van Rossum <guido@python.org>
parents:
1784
diff
changeset
|
1210 |
|
53d17c04b42f
Added obfuxcated lambda's by Ulf Bertelt
Guido van Rossum <guido@python.org>
parents:
1784
diff
changeset
|
1211 Don't try this at home, kids! |
|
53d17c04b42f
Added obfuxcated lambda's by Ulf Bertelt
Guido van Rossum <guido@python.org>
parents:
1784
diff
changeset
|
1212 |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1213 4.16. Q. Is there an equivalent of C's "?:" ternary operator? |
|
1902
53d17c04b42f
Added obfuxcated lambda's by Ulf Bertelt
Guido van Rossum <guido@python.org>
parents:
1784
diff
changeset
|
1214 |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1215 A. Not directly. In many cases you can mimic a?b:c with "a and b or |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1216 c", but there's a flaw: if b is zero (or empty, or None -- anything |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1217 that tests false) then c will be selected instead. In many cases you |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1218 can prove by looking at the code that this can't happen (e.g. because |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1219 b is a constant or has a type that can never be false), but in general |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1220 this can be a problem. |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1221 |
|
4278
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1222 Tim Peters (who wishes it was Steve Majewski) suggested the following |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1223 solution: (a and [b] or [c])[0]. Because [b] is a singleton list it |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1224 is never false, so the wrong path is never taken; then applying [0] to |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1225 the whole thing gets the b or c that you really wanted. Ugly, but it |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1226 gets you there in the rare cases where it is really inconvenient to |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1227 rewrite your code using 'if'. |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1228 |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1229 4.17. Q. My class defines __del__ but it is not called when I delete the |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1230 object. |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1231 |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1232 A. There are several possible reasons for this. |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1233 |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1234 - The del statement does not necessarily call __del__ -- it simply |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1235 decrements the object's reference count, and if this reaches zero |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1236 __del__ is called. |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1237 |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1238 - If your data structures contain circular links (e.g. a tree where |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1239 each child has a parent pointer and each parent has a list of |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1240 children) the reference counts will never go back to zero. You'll |
| 1942 | 1241 have to define an explicit close() method which removes those |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1242 pointers. Please don't ever call __del__ directly -- __del__ should |
| 1942 | 1243 call close() and close() should make sure that it can be called more |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1244 than once for the same object. |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1245 |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1246 - If the object has ever been a local variable (or argument, which is |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1247 really the same thing) to a function that caught an expression in an |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1248 except clause, chances are that a reference to the object still exists |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1249 in that function's stack frame as contained in the stack trace. |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1250 Normally, deleting (better: assigning None to) sys.exc_traceback will |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1251 take care of this. If you a stack was printed for an unhandled |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1252 exception in an interactive interpreter, delete sys.last_traceback |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1253 instead. |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1254 |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1255 - There is code that deletes all objects when the interpreter exits, |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1256 but if your Python has been configured to support threads, it is not |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1257 called (because other threads may still be active). You can define |
| 1942 | 1258 your own cleanup function using sys.exitfunc (see question 4.4). |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1259 |
|
4250
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
1260 - Finally, if your __del__ method raises an exception, this will be |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
1261 ignored. Starting with Python 1.4beta3, a warning message is printed |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
1262 to sys.stderr when this happens. |
| 2048 | 1263 |
| 1264 4.18. Q. How do I change the shell environment for programs called | |
| 1265 using os.popen() or os.system()? Changing os.environ doesn't work. | |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1266 |
|
5127
f22213192531
Change the question about os.environ changes not working -- it now
Guido van Rossum <guido@python.org>
parents:
5126
diff
changeset
|
1267 A. You must be using either a version of python before 1.4, or on a |
|
f22213192531
Change the question about os.environ changes not working -- it now
Guido van Rossum <guido@python.org>
parents:
5126
diff
changeset
|
1268 (rare) system that doesn't have the putenv() library function. |
|
f22213192531
Change the question about os.environ changes not working -- it now
Guido van Rossum <guido@python.org>
parents:
5126
diff
changeset
|
1269 |
|
f22213192531
Change the question about os.environ changes not working -- it now
Guido van Rossum <guido@python.org>
parents:
5126
diff
changeset
|
1270 Before Python 1.4, modifying the environment passed to subshells was |
|
f22213192531
Change the question about os.environ changes not working -- it now
Guido van Rossum <guido@python.org>
parents:
5126
diff
changeset
|
1271 left out of the interpreter because there seemed to be no |
|
f22213192531
Change the question about os.environ changes not working -- it now
Guido van Rossum <guido@python.org>
parents:
5126
diff
changeset
|
1272 well-established portable way to do it (in particular, some systems, |
|
f22213192531
Change the question about os.environ changes not working -- it now
Guido van Rossum <guido@python.org>
parents:
5126
diff
changeset
|
1273 have putenv(), others have setenv(), and some have none at all). As |
|
f22213192531
Change the question about os.environ changes not working -- it now
Guido van Rossum <guido@python.org>
parents:
5126
diff
changeset
|
1274 of Python 1.4, almost all Unix systems *do* have putenv(), and so does |
|
f22213192531
Change the question about os.environ changes not working -- it now
Guido van Rossum <guido@python.org>
parents:
5126
diff
changeset
|
1275 the Win32 API, and thus the os module was modified so that changes to |
|
f22213192531
Change the question about os.environ changes not working -- it now
Guido van Rossum <guido@python.org>
parents:
5126
diff
changeset
|
1276 os.environ are trapped and the corresponding putenv() call is made. |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1277 |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1278 4.19. Q. What is a class? |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1279 |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1280 A. A class is the particular object type that is created by executing |
|
2208
c68a0113b75a
intermediate version -- why not...
Guido van Rossum <guido@python.org>
parents:
2048
diff
changeset
|
1281 a class statement. Class objects are used as templates, to create |
|
c68a0113b75a
intermediate version -- why not...
Guido van Rossum <guido@python.org>
parents:
2048
diff
changeset
|
1282 class instance objects, which embody both the data structure and |
|
c68a0113b75a
intermediate version -- why not...
Guido van Rossum <guido@python.org>
parents:
2048
diff
changeset
|
1283 program routines specific to a datatype. |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1284 |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1285 4.20. Q. What is a method? |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1286 |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1287 A. A method is a function that you normally call as |
|
2208
c68a0113b75a
intermediate version -- why not...
Guido van Rossum <guido@python.org>
parents:
2048
diff
changeset
|
1288 x.name(arguments...) for some object x. The term is used for methods |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1289 of classes and class instances as well as for methods of built-in |
|
2208
c68a0113b75a
intermediate version -- why not...
Guido van Rossum <guido@python.org>
parents:
2048
diff
changeset
|
1290 objects. (The latter have a completely different implementation and |
|
c68a0113b75a
intermediate version -- why not...
Guido van Rossum <guido@python.org>
parents:
2048
diff
changeset
|
1291 only share the way their calls look in Python code.) Methods of |
|
c68a0113b75a
intermediate version -- why not...
Guido van Rossum <guido@python.org>
parents:
2048
diff
changeset
|
1292 classes (and class instances) are defined as functions inside the |
|
c68a0113b75a
intermediate version -- why not...
Guido van Rossum <guido@python.org>
parents:
2048
diff
changeset
|
1293 class definition. |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1294 |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1295 4.21. Q. What is self? |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1296 |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1297 A. Self is merely a conventional name for the first argument of a |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1298 method -- i.e. a function defined inside a class definition. A method |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1299 defined as meth(self, a, b, c) should be called as x.meth(a, b, c) for |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1300 some instance x of the class in which the definition occurs; |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1301 the called method will think it is called as meth(x, a, b, c). |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1302 |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1303 4.22. Q. What is a unbound method? |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1304 |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1305 A. An unbound method is a method defined in a class that is not yet |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1306 bound to an instance. You get an unbound method if you ask for a |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1307 class attribute that happens to be a function. You get a bound method |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1308 if you ask for an instance attribute. A bound method knows which |
| 1942 | 1309 instance it belongs to and calling it supplies the instance automatically; |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1310 an unbound method only knows which class it wants for its first |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1311 argument (a derived class is also OK). Calling an unbound method |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1312 doesn't "magically" derive the first argument from the context -- you |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1313 have to provide it explicitly. |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1314 |
| 2048 | 1315 4.23. Q. How do I call a method defined in a base class from a derived |
| 1316 class that overrides it? | |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1317 |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1318 A. If your class definition starts with "class Derived(Base): ..." |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1319 then you can call method meth defined in Base (or one of Base's base |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1320 classes) as Base.meth(self, arguments...). Here, Base.meth is an |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1321 unbound method (see previous question). |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1322 |
| 2048 | 1323 4.24. Q. How do I call a method from a base class without using the |
| 1324 name of the base class? | |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1325 |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1326 A. DON'T DO THIS. REALLY. I MEAN IT. It appears that you could call |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1327 self.__class__.__bases__[0].meth(self, arguments...) but this fails when |
| 1942 | 1328 a doubly-derived method is derived from your class: for its instances, |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1329 self.__class__.__bases__[0] is your class, not its base class -- so |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1330 (assuming you are doing this from within Derived.meth) you would start |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1331 a recursive call. |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1332 |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1333 4.25. Q. How can I organize my code to make it easier to change the base |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1334 class? |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1335 |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1336 A. You could define an alias for the base class, assign the real base |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1337 class to it before your class definition, and use the alias throughout |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1338 your class. Then all you have to change is the value assigned to the |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1339 alias. Incidentally, this trick is also handy if you want to decide |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1340 dynamically (e.g. depending on availability of resources) which base |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1341 class to use. Example: |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1342 |
|
4278
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1343 BaseAlias = <real base class> |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1344 class Derived(BaseAlias): |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1345 def meth(self): |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1346 BaseAlias.meth(self) |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1347 ... |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1348 |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1349 4.26. Q. How can I find the methods or attributes of an object? |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1350 |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1351 A. This depends on the object type. |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1352 |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1353 For an instance x of a user-defined class, instance attributes are |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1354 found in the dictionary x.__dict__, and methods and attributes defined |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1355 by its class are found in x.__class__.__bases__[i].__dict__ (for i in |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1356 range(len(x.__class__.__bases__))). You'll have to walk the tree of |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1357 base classes to find *all* class methods and attributes. |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1358 |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1359 Many, but not all built-in types define a list of their method names |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1360 in x.__methods__, and if they have data attributes, their names may be |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1361 found in x.__members__. However this is only a convention. |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1362 |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1363 For more information, read the source of the standard (but |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1364 undocumented) module newdir. |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1365 |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1366 4.27. Q. I can't seem to use os.read() on a pipe created with os.popen(). |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1367 |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1368 A. os.read() is a low-level function which takes a file descriptor (a |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1369 small integer). os.popen() creates a high-level file object -- the |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1370 same type used for sys.std{in,out,err} and returned by the builtin |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1371 open() function. Thus, to read n bytes from a pipe p created with |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1372 os.popen(), you need to use p.read(n). |
| 1529 | 1373 |
| 1942 | 1374 4.28. Q. How can I create a stand-alone binary from a Python script? |
| 1375 | |
| 1376 The demo script "Demo/scripts/freeze.py" does what you want. (It's | |
| 1377 actually not a demo but a support tool -- there is some extra code in | |
| 1378 the interpreter to accommodate it.) It requires that you have the | |
| 1379 Python build tree handy, complete with all the lib*.a files. | |
| 1380 | |
| 1381 This works by scanning your source recursively for import statements | |
| 1382 (both forms) and looking for the modules on the standard Python path | |
| 1383 as well as in the source directory (for built-in modules). It then | |
| 1384 "compiles" the modules written in Python to C code (array initializers | |
| 1385 that can be turned into code objects using the marshal module) and | |
| 1386 creates a custom-made config file that only contains those built-in | |
| 1387 modules which are actually used in the program. It then compiles the | |
| 1388 generated C code and links it with the rest of the Python interpreter | |
| 1389 to form a self-contained binary which acts exactly like your script. | |
| 1390 | |
|
2716
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
1391 Hint: the freeze program only works if your script's filename ends in |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
1392 ".py". |
| 1942 | 1393 |
|
2716
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
1394 4.29. Q. What WWW tools are there for Python? |
| 1942 | 1395 |
|
4250
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
1396 A. See the chapter titled "Internet and WWW" in the Library Reference |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
1397 Manual. There's also a web browser written in Python, called Grail -- |
|
4563
ea458933fc2a
monty -> grail in Grail URL.
Guido van Rossum <guido@python.org>
parents:
4543
diff
changeset
|
1398 see <URL:http://grail.cnri.reston.va.us/grail/>. |
| 1942 | 1399 |
| 1400 Steve Miale <smiale@cs.indiana.edu> has written a modular WWW browser | |
| 1401 called Dancer. An alpha version can be FTP'ed from | |
| 2048 | 1402 <URL:ftp://ftp.cs.indiana.edu/pub/smiale/dancer.tar.gz>. (There are a |
| 1403 few articles about Dancer in the (hyper)mail archive | |
| 1404 <URL:http://www.cwi.nl/~guido/hypermail/python-1994q3/index.html>.) | |
| 1942 | 1405 |
|
2716
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
1406 4.30. Q. How do I run a subprocess with pipes connected to both input |
|
2208
c68a0113b75a
intermediate version -- why not...
Guido van Rossum <guido@python.org>
parents:
2048
diff
changeset
|
1407 and output? |
|
c68a0113b75a
intermediate version -- why not...
Guido van Rossum <guido@python.org>
parents:
2048
diff
changeset
|
1408 |
|
c68a0113b75a
intermediate version -- why not...
Guido van Rossum <guido@python.org>
parents:
2048
diff
changeset
|
1409 A. This is really a UNIX question. Also, in general, it is unwise to |
|
c68a0113b75a
intermediate version -- why not...
Guido van Rossum <guido@python.org>
parents:
2048
diff
changeset
|
1410 do so, because you can easily cause a deadlock where the parent |
|
c68a0113b75a
intermediate version -- why not...
Guido van Rossum <guido@python.org>
parents:
2048
diff
changeset
|
1411 process is blocked waiting for output from the child, while the child |
|
c68a0113b75a
intermediate version -- why not...
Guido van Rossum <guido@python.org>
parents:
2048
diff
changeset
|
1412 is blocked waiting for input from the child. This can be caused |
|
c68a0113b75a
intermediate version -- why not...
Guido van Rossum <guido@python.org>
parents:
2048
diff
changeset
|
1413 because the parent expects the child to output more text than it does, |
|
c68a0113b75a
intermediate version -- why not...
Guido van Rossum <guido@python.org>
parents:
2048
diff
changeset
|
1414 or it can be caused by data being stuck in stdio buffers due to lack |
|
c68a0113b75a
intermediate version -- why not...
Guido van Rossum <guido@python.org>
parents:
2048
diff
changeset
|
1415 of flushing. The Python parent can of course explicitly flush the data |
|
c68a0113b75a
intermediate version -- why not...
Guido van Rossum <guido@python.org>
parents:
2048
diff
changeset
|
1416 it sends to the child before it reads any output, but if the child is |
|
c68a0113b75a
intermediate version -- why not...
Guido van Rossum <guido@python.org>
parents:
2048
diff
changeset
|
1417 a naive C program it can easily have been written to never explicitly |
|
c68a0113b75a
intermediate version -- why not...
Guido van Rossum <guido@python.org>
parents:
2048
diff
changeset
|
1418 flush its output, even if it is interactive, since flushing is |
|
c68a0113b75a
intermediate version -- why not...
Guido van Rossum <guido@python.org>
parents:
2048
diff
changeset
|
1419 normally automatic. |
|
c68a0113b75a
intermediate version -- why not...
Guido van Rossum <guido@python.org>
parents:
2048
diff
changeset
|
1420 |
|
c68a0113b75a
intermediate version -- why not...
Guido van Rossum <guido@python.org>
parents:
2048
diff
changeset
|
1421 In many cases, all you really need is to run some data through a |
|
c68a0113b75a
intermediate version -- why not...
Guido van Rossum <guido@python.org>
parents:
2048
diff
changeset
|
1422 command and get the result back. Unless the data is infinite in size, |
|
c68a0113b75a
intermediate version -- why not...
Guido van Rossum <guido@python.org>
parents:
2048
diff
changeset
|
1423 the easiest (and often the most efficient!) way to do this is to write |
|
c68a0113b75a
intermediate version -- why not...
Guido van Rossum <guido@python.org>
parents:
2048
diff
changeset
|
1424 it to a temporary file and run the command with that temporary file as |
|
c68a0113b75a
intermediate version -- why not...
Guido van Rossum <guido@python.org>
parents:
2048
diff
changeset
|
1425 input. The standard module tempfile exports a function mktemp() which |
|
c68a0113b75a
intermediate version -- why not...
Guido van Rossum <guido@python.org>
parents:
2048
diff
changeset
|
1426 generates unique temporary file names. |
|
c68a0113b75a
intermediate version -- why not...
Guido van Rossum <guido@python.org>
parents:
2048
diff
changeset
|
1427 |
|
c68a0113b75a
intermediate version -- why not...
Guido van Rossum <guido@python.org>
parents:
2048
diff
changeset
|
1428 If after reading all of the above you still want to connect two pipes |
|
c68a0113b75a
intermediate version -- why not...
Guido van Rossum <guido@python.org>
parents:
2048
diff
changeset
|
1429 to a subprocess's standard input and output, here's a simple solution, |
|
c68a0113b75a
intermediate version -- why not...
Guido van Rossum <guido@python.org>
parents:
2048
diff
changeset
|
1430 due to Jack Jansen: |
|
c68a0113b75a
intermediate version -- why not...
Guido van Rossum <guido@python.org>
parents:
2048
diff
changeset
|
1431 |
|
3207
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
1432 import os |
|
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
1433 import sys |
|
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
1434 import string |
|
2208
c68a0113b75a
intermediate version -- why not...
Guido van Rossum <guido@python.org>
parents:
2048
diff
changeset
|
1435 |
|
3207
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
1436 MAXFD = 100 # Max number of file descriptors in this system |
|
2208
c68a0113b75a
intermediate version -- why not...
Guido van Rossum <guido@python.org>
parents:
2048
diff
changeset
|
1437 |
|
3207
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
1438 def popen2(cmd): |
|
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
1439 cmd = string.split(cmd) |
|
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
1440 p2cread, p2cwrite = os.pipe() |
|
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
1441 c2pread, c2pwrite = os.pipe() |
|
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
1442 pid = os.fork() |
|
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
1443 if pid == 0: |
|
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
1444 # Child |
|
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
1445 os.close(0) |
|
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
1446 os.close(1) |
|
3727
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1447 if os.dup(p2cread) != 0: |
|
3207
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
1448 sys.stderr.write('popen2: bad read dup\n') |
|
3727
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1449 if os.dup(c2pwrite) != 1: |
|
3207
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
1450 sys.stderr.write('popen2: bad write dup\n') |
|
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
1451 for i in range(3, MAXFD): |
|
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
1452 try: |
|
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
1453 os.close(i) |
|
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
1454 except: |
|
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
1455 pass |
|
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
1456 try: |
|
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
1457 os.execv(cmd[0], cmd) |
|
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
1458 finally: |
|
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
1459 os._exit(1) |
|
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
1460 os.close(p2cread) |
|
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
1461 tochild = os.fdopen(p2cwrite, 'w') |
|
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
1462 os.close(c2pwrite) |
|
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
1463 fromchild = os.fdopen(c2pread, 'r') |
|
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
1464 return fromchild, tochild |
|
2208
c68a0113b75a
intermediate version -- why not...
Guido van Rossum <guido@python.org>
parents:
2048
diff
changeset
|
1465 |
|
c68a0113b75a
intermediate version -- why not...
Guido van Rossum <guido@python.org>
parents:
2048
diff
changeset
|
1466 Note that many interactive programs (e.g. vi) don't work well with |
|
c68a0113b75a
intermediate version -- why not...
Guido van Rossum <guido@python.org>
parents:
2048
diff
changeset
|
1467 pipes substituted for standard input and output. You will have to use |
|
c68a0113b75a
intermediate version -- why not...
Guido van Rossum <guido@python.org>
parents:
2048
diff
changeset
|
1468 pseudo ttys ("ptys") instead of pipes. There is some undocumented |
|
c68a0113b75a
intermediate version -- why not...
Guido van Rossum <guido@python.org>
parents:
2048
diff
changeset
|
1469 code to use these in the library module pty.py -- I'm afraid you're on |
| 2855 | 1470 your own here. |
| 1471 | |
| 1472 A different answer is a Python interface to Don Libes' "expect" | |
| 1473 library. A prerelease of this is available on the Python ftp mirror | |
| 1474 sites in the contrib subdirectory as expy-0.3.tar.gz, e.g. | |
| 1475 <URL:ftp://ftp.python.org/pub/python/contrib/expy-0.3.tar.gz>. | |
|
2208
c68a0113b75a
intermediate version -- why not...
Guido van Rossum <guido@python.org>
parents:
2048
diff
changeset
|
1476 |
|
2716
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
1477 4.31. Q. How do I call a function if I have the arguments in a tuple? |
|
2660
4eb6ddb9e961
Some more changes for 1.2
Guido van Rossum <guido@python.org>
parents:
2526
diff
changeset
|
1478 |
|
4eb6ddb9e961
Some more changes for 1.2
Guido van Rossum <guido@python.org>
parents:
2526
diff
changeset
|
1479 A. Use the built-in function apply(). For instance, |
|
4eb6ddb9e961
Some more changes for 1.2
Guido van Rossum <guido@python.org>
parents:
2526
diff
changeset
|
1480 |
|
4eb6ddb9e961
Some more changes for 1.2
Guido van Rossum <guido@python.org>
parents:
2526
diff
changeset
|
1481 func(1, 2, 3) |
|
4eb6ddb9e961
Some more changes for 1.2
Guido van Rossum <guido@python.org>
parents:
2526
diff
changeset
|
1482 |
|
4eb6ddb9e961
Some more changes for 1.2
Guido van Rossum <guido@python.org>
parents:
2526
diff
changeset
|
1483 is equivalent to |
|
4eb6ddb9e961
Some more changes for 1.2
Guido van Rossum <guido@python.org>
parents:
2526
diff
changeset
|
1484 |
|
4eb6ddb9e961
Some more changes for 1.2
Guido van Rossum <guido@python.org>
parents:
2526
diff
changeset
|
1485 args = (1, 2, 3) |
|
4eb6ddb9e961
Some more changes for 1.2
Guido van Rossum <guido@python.org>
parents:
2526
diff
changeset
|
1486 apply(func, args) |
|
4eb6ddb9e961
Some more changes for 1.2
Guido van Rossum <guido@python.org>
parents:
2526
diff
changeset
|
1487 |
|
4eb6ddb9e961
Some more changes for 1.2
Guido van Rossum <guido@python.org>
parents:
2526
diff
changeset
|
1488 Note that func(args) is not the same -- it calls func() with exactly |
|
4eb6ddb9e961
Some more changes for 1.2
Guido van Rossum <guido@python.org>
parents:
2526
diff
changeset
|
1489 one argument, the tuple args, instead of three arguments, the integers |
|
4eb6ddb9e961
Some more changes for 1.2
Guido van Rossum <guido@python.org>
parents:
2526
diff
changeset
|
1490 1, 2 and 3. |
|
4eb6ddb9e961
Some more changes for 1.2
Guido van Rossum <guido@python.org>
parents:
2526
diff
changeset
|
1491 |
|
2716
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
1492 4.32. Q. How do I enable font-lock-mode for Python in Emacs? |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
1493 |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
1494 A. Assuming you're already using python-mode and font-lock-mode |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
1495 separately, all you need to do is put this in your .emacs file: |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
1496 |
|
3207
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
1497 (defun my-python-mode-hook () |
|
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
1498 (setq font-lock-keywords python-font-lock-keywords) |
|
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
1499 (font-lock-mode 1)) |
|
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
1500 (add-hook 'python-mode-hook 'my-python-mode-hook) |
|
2716
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
1501 |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
1502 4.33. Q. Is there an inverse to the format operator (a la C's scanf())? |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
1503 |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
1504 A. Not as such. |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
1505 |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
1506 For simple input parsing, the easiest approach is usually to split |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
1507 the line into whitespace-delimited words using string.split(), and to |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
1508 convert decimal strings to numeric values using string.atoi(), |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
1509 string.atol() or string.atof(). (Python's atoi() is 32-bit and its |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
1510 atol() is arbitrary precision.) If you want to use another delimiter |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
1511 than whitespace, use string.splitfield() (possibly combining it with |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
1512 string.strip() which removes surrounding whitespace from a string). |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
1513 |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
1514 For more complicated input parsing, regular expressions (see module |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
1515 regex) are better suited and more powerful than C's scanf(). |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
1516 |
|
3727
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1517 4.34. Q. Can I have Tk events handled while waiting for I/O? |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1518 |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1519 A. Yes, and you don't even need threads! But you'll have to |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1520 restructure your I/O code a bit. Tk has the equivalent of Xt's |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1521 XtAddInput() call, which allows you to register a callback function |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1522 which will be called from the Tk mainloop when I/O is possible on a |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1523 file descriptor. Here's what you need: |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1524 |
|
4278
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1525 from Tkinter import tkinter |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1526 tkinter.createfilehandler(file, mask, callback) |
|
3727
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1527 |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1528 The file may be a Python file or socket object (actually, anything |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1529 with a fileno() method), or an integer file descriptor. The mask is |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1530 one of the constants tkinter.READABLE or tkinter.WRITABLE. The |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1531 callback is called as follows: |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1532 |
|
4278
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1533 callback(file, mask) |
|
3727
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1534 |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1535 You must unregister the callback when you're done, using |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1536 |
|
4278
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1537 tkinter.deletefilehandler(file) |
|
3727
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1538 |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1539 Note: since you don't know *how many bytes* are available for reading, |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1540 you can't use the Python file object's read or readline methods, since |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1541 these will insist on reading a predefined number of bytes. For |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1542 sockets, the recv() or recvfrom() methods will work fine; for other |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1543 files, use os.read(file.fileno(), maxbytecount). |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1544 |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1545 4.35. Q. How do I write a function with output parameters (call by reference)? |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1546 |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1547 A. [Mark Lutz] The thing to remember is that arguments are passed by |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1548 assignment in Python. Since assignment just creates references to |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1549 objects, there's no alias between an argument name in the caller and |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1550 callee, and so no call-by-reference per se. But you can simulate it |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1551 in a number of ways: |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1552 |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1553 1) By using global variables; but you probably shouldn't :-) |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1554 |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1555 2) By passing a mutable (changeable in-place) object: |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1556 |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1557 def func1(a): |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1558 a[0] = 'new-value' # 'a' references a mutable list |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1559 a[1] = a[1] + 1 # changes a shared object |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1560 |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1561 args = ['old-value', 99] |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1562 func1(args) |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1563 print args[0], args[1] # output: new-value 100 |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1564 |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1565 3) By return a tuple, holding the final values of arguments: |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1566 |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1567 def func2(a, b): |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1568 a = 'new-value' # a and b are local names |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1569 b = b + 1 # assigned to new objects |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1570 return a, b # return new values |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1571 |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1572 x, y = 'old-value', 99 |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1573 x, y = func2(x, y) |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1574 print x, y # output: new-value 100 |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1575 |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1576 4) And other ideas that fall-out from Python's object model. For |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1577 instance, it might be clearer to pass in a mutable dictionary: |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1578 |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1579 def func3(args): |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1580 args['a'] = 'new-value' # args is a mutable dictionary |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1581 args['b'] = args['b'] + 1 # change it in-place |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1582 |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1583 args = {'a':' old-value', 'b': 99} |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1584 func3(args) |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1585 print args['a'], args['b'] |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1586 |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1587 5) Or bundle-up values in a class instance: |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1588 |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1589 class callByRef: |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1590 def __init__(self, **args): |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1591 for (key, value) in args.items(): |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1592 setattr(self, key, value) |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1593 |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1594 def func4(args): |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1595 args.a = 'new-value' # args is a mutable callByRef |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1596 args.b = args.b + 1 # change object in-place |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1597 |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1598 args = callByRef(a='old-value', b=99) |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1599 func4(args) |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1600 print args.a, args.b |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1601 |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1602 But there's probably no good reason to get this complicated :-). |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1603 |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1604 [Python' author favors solution 3 in most cases.] |
|
a10a0f6014c4
Some updates. Still out of date.
Guido van Rossum <guido@python.org>
parents:
3233
diff
changeset
|
1605 |
|
3865
4591035228a7
Added two new questions; about globals/locals and about recursive imports.
Guido van Rossum <guido@python.org>
parents:
3727
diff
changeset
|
1606 4.36. Q. Please explain the rules for local and global variables in Python. |
|
4591035228a7
Added two new questions; about globals/locals and about recursive imports.
Guido van Rossum <guido@python.org>
parents:
3727
diff
changeset
|
1607 |
|
4591035228a7
Added two new questions; about globals/locals and about recursive imports.
Guido van Rossum <guido@python.org>
parents:
3727
diff
changeset
|
1608 A. [Ken Manheimer] In Python, procedure variables are implicitly |
|
4591035228a7
Added two new questions; about globals/locals and about recursive imports.
Guido van Rossum <guido@python.org>
parents:
3727
diff
changeset
|
1609 global, unless they assigned anywhere within the block. In that case |
|
4591035228a7
Added two new questions; about globals/locals and about recursive imports.
Guido van Rossum <guido@python.org>
parents:
3727
diff
changeset
|
1610 they are implicitly local, and you need to explicitly declare them as |
|
4591035228a7
Added two new questions; about globals/locals and about recursive imports.
Guido van Rossum <guido@python.org>
parents:
3727
diff
changeset
|
1611 'global'. |
|
4591035228a7
Added two new questions; about globals/locals and about recursive imports.
Guido van Rossum <guido@python.org>
parents:
3727
diff
changeset
|
1612 |
|
4591035228a7
Added two new questions; about globals/locals and about recursive imports.
Guido van Rossum <guido@python.org>
parents:
3727
diff
changeset
|
1613 Though a bit surprising at first, a moments consideration explains |
|
4591035228a7
Added two new questions; about globals/locals and about recursive imports.
Guido van Rossum <guido@python.org>
parents:
3727
diff
changeset
|
1614 this. On one hand, requirement of 'global' for assigned vars provides |
|
4591035228a7
Added two new questions; about globals/locals and about recursive imports.
Guido van Rossum <guido@python.org>
parents:
3727
diff
changeset
|
1615 a bar against unintended side-effects. On the other hand, if global |
|
4591035228a7
Added two new questions; about globals/locals and about recursive imports.
Guido van Rossum <guido@python.org>
parents:
3727
diff
changeset
|
1616 were required for all global references, you'd be using global all the |
|
4591035228a7
Added two new questions; about globals/locals and about recursive imports.
Guido van Rossum <guido@python.org>
parents:
3727
diff
changeset
|
1617 time. Eg, you'd have to declare as global every reference to a |
|
4591035228a7
Added two new questions; about globals/locals and about recursive imports.
Guido van Rossum <guido@python.org>
parents:
3727
diff
changeset
|
1618 builtin function, or to a component of an imported module. This |
|
4591035228a7
Added two new questions; about globals/locals and about recursive imports.
Guido van Rossum <guido@python.org>
parents:
3727
diff
changeset
|
1619 clutter would defeat the usefulness of the 'global' declaration for |
|
4591035228a7
Added two new questions; about globals/locals and about recursive imports.
Guido van Rossum <guido@python.org>
parents:
3727
diff
changeset
|
1620 identifying side-effects. |
|
4591035228a7
Added two new questions; about globals/locals and about recursive imports.
Guido van Rossum <guido@python.org>
parents:
3727
diff
changeset
|
1621 |
|
4591035228a7
Added two new questions; about globals/locals and about recursive imports.
Guido van Rossum <guido@python.org>
parents:
3727
diff
changeset
|
1622 4.37. Q. How can I have modules that mutually import each other? |
|
4591035228a7
Added two new questions; about globals/locals and about recursive imports.
Guido van Rossum <guido@python.org>
parents:
3727
diff
changeset
|
1623 |
|
4591035228a7
Added two new questions; about globals/locals and about recursive imports.
Guido van Rossum <guido@python.org>
parents:
3727
diff
changeset
|
1624 A. Jim Roskind recommends the following order in each module: |
|
4591035228a7
Added two new questions; about globals/locals and about recursive imports.
Guido van Rossum <guido@python.org>
parents:
3727
diff
changeset
|
1625 |
|
4591035228a7
Added two new questions; about globals/locals and about recursive imports.
Guido van Rossum <guido@python.org>
parents:
3727
diff
changeset
|
1626 First: all exports (like globals, functions, and classes that don't |
|
4591035228a7
Added two new questions; about globals/locals and about recursive imports.
Guido van Rossum <guido@python.org>
parents:
3727
diff
changeset
|
1627 need imported bases classes). |
|
4591035228a7
Added two new questions; about globals/locals and about recursive imports.
Guido van Rossum <guido@python.org>
parents:
3727
diff
changeset
|
1628 |
|
4591035228a7
Added two new questions; about globals/locals and about recursive imports.
Guido van Rossum <guido@python.org>
parents:
3727
diff
changeset
|
1629 Then: all import statements. |
|
4591035228a7
Added two new questions; about globals/locals and about recursive imports.
Guido van Rossum <guido@python.org>
parents:
3727
diff
changeset
|
1630 |
|
4591035228a7
Added two new questions; about globals/locals and about recursive imports.
Guido van Rossum <guido@python.org>
parents:
3727
diff
changeset
|
1631 Finally: all active code (including globals that are initialized from |
|
4591035228a7
Added two new questions; about globals/locals and about recursive imports.
Guido van Rossum <guido@python.org>
parents:
3727
diff
changeset
|
1632 imported values). |
|
4591035228a7
Added two new questions; about globals/locals and about recursive imports.
Guido van Rossum <guido@python.org>
parents:
3727
diff
changeset
|
1633 |
|
4591035228a7
Added two new questions; about globals/locals and about recursive imports.
Guido van Rossum <guido@python.org>
parents:
3727
diff
changeset
|
1634 Python's author doesn't like this approach much because the imports |
|
4591035228a7
Added two new questions; about globals/locals and about recursive imports.
Guido van Rossum <guido@python.org>
parents:
3727
diff
changeset
|
1635 appear in a strange place, but has to admit that it works. His |
|
4591035228a7
Added two new questions; about globals/locals and about recursive imports.
Guido van Rossum <guido@python.org>
parents:
3727
diff
changeset
|
1636 recommended strategy is to avoid all uses of "from <module> import *" |
|
4591035228a7
Added two new questions; about globals/locals and about recursive imports.
Guido van Rossum <guido@python.org>
parents:
3727
diff
changeset
|
1637 (so everything from an imported module is referenced as |
|
4591035228a7
Added two new questions; about globals/locals and about recursive imports.
Guido van Rossum <guido@python.org>
parents:
3727
diff
changeset
|
1638 <module>.<name>) and to place all code inside functions. |
|
4591035228a7
Added two new questions; about globals/locals and about recursive imports.
Guido van Rossum <guido@python.org>
parents:
3727
diff
changeset
|
1639 Initializations of global variables and class variables should use |
|
4591035228a7
Added two new questions; about globals/locals and about recursive imports.
Guido van Rossum <guido@python.org>
parents:
3727
diff
changeset
|
1640 constants or built-in functions only. |
|
4591035228a7
Added two new questions; about globals/locals and about recursive imports.
Guido van Rossum <guido@python.org>
parents:
3727
diff
changeset
|
1641 |
|
4250
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
1642 4.38. Q. How do I copy an object in Python? |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
1643 |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
1644 A. There is no generic copying operation built into Python, however |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
1645 most object types have some way to create a clone. Here's how for the |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
1646 most common objects: |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
1647 |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
1648 - For immutable objects (numbers, strings, tuples), cloning is |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
1649 unnecessary since their value can't change. |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
1650 |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
1651 - For lists (and generally for mutable sequence types), a clone is |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
1652 created by the expression l[:]. |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
1653 |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
1654 - For dictionaries, the following function returns a clone: |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
1655 |
|
4278
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1656 def dictclone(o): |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1657 n = {} |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1658 for k in o.keys(): n[k] = o[k] |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
1659 return n |
|
4250
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
1660 |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
1661 - Finally, for generic objects, the "copy" module defines two |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
1662 functions for copying objects. copy.copy(x) returns a copy as shown |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
1663 by the above rules. copy.deepcopy(x) also copies the elements of |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
1664 composite objects. See the section on this module in the Library |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
1665 Reference Manual. |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
1666 |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
1667 4.39. Q. How to implement persistent objects in Python? (Persistent == |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
1668 automatically saved to and restored from disk.) |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
1669 |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
1670 A. The library module "pickle" now solves this in a very general way |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
1671 (though you still can't store things like open files, sockests or |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
1672 windows), and the library module "shelve" uses pickle and (g)dbm to |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
1673 create presistent mappings containing arbitrary Python objects. |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
1674 |
|
4438
e88b3215e94a
Added question about error from misuse of mangled names.
Guido van Rossum <guido@python.org>
parents:
4408
diff
changeset
|
1675 4.40. Q. I try to use __spam and I get an error about _SomeClassName__spam. |
|
e88b3215e94a
Added question about error from misuse of mangled names.
Guido van Rossum <guido@python.org>
parents:
4408
diff
changeset
|
1676 |
|
e88b3215e94a
Added question about error from misuse of mangled names.
Guido van Rossum <guido@python.org>
parents:
4408
diff
changeset
|
1677 A. Variables with double leading underscore are "mangled" to provide a |
|
e88b3215e94a
Added question about error from misuse of mangled names.
Guido van Rossum <guido@python.org>
parents:
4408
diff
changeset
|
1678 simple but effective way to define class private variables. See the |
|
e88b3215e94a
Added question about error from misuse of mangled names.
Guido van Rossum <guido@python.org>
parents:
4408
diff
changeset
|
1679 chapter "New in Release 1.4" in the Python Tutorial. |
|
e88b3215e94a
Added question about error from misuse of mangled names.
Guido van Rossum <guido@python.org>
parents:
4408
diff
changeset
|
1680 |
|
4543
e52054440efc
Added os.remove()/unlink(), rmdir(), rename(), and [f]truncate().
Guido van Rossum <guido@python.org>
parents:
4542
diff
changeset
|
1681 4.41. Q. How do I delete a file? And other file questions. |
|
e52054440efc
Added os.remove()/unlink(), rmdir(), rename(), and [f]truncate().
Guido van Rossum <guido@python.org>
parents:
4542
diff
changeset
|
1682 |
|
e52054440efc
Added os.remove()/unlink(), rmdir(), rename(), and [f]truncate().
Guido van Rossum <guido@python.org>
parents:
4542
diff
changeset
|
1683 A. Use os.remove(filename) or os.unlink(filename); for documentation, |
|
e52054440efc
Added os.remove()/unlink(), rmdir(), rename(), and [f]truncate().
Guido van Rossum <guido@python.org>
parents:
4542
diff
changeset
|
1684 see the posix section of the library manual. They are the same, |
|
e52054440efc
Added os.remove()/unlink(), rmdir(), rename(), and [f]truncate().
Guido van Rossum <guido@python.org>
parents:
4542
diff
changeset
|
1685 unlink() is simply the Unix name for this function. In earlier |
|
e52054440efc
Added os.remove()/unlink(), rmdir(), rename(), and [f]truncate().
Guido van Rossum <guido@python.org>
parents:
4542
diff
changeset
|
1686 versions of Python, only os.unlink() was available. |
|
e52054440efc
Added os.remove()/unlink(), rmdir(), rename(), and [f]truncate().
Guido van Rossum <guido@python.org>
parents:
4542
diff
changeset
|
1687 |
|
e52054440efc
Added os.remove()/unlink(), rmdir(), rename(), and [f]truncate().
Guido van Rossum <guido@python.org>
parents:
4542
diff
changeset
|
1688 To remove a directory, use os.rmdir(); use os.mkdir() to create one. |
|
e52054440efc
Added os.remove()/unlink(), rmdir(), rename(), and [f]truncate().
Guido van Rossum <guido@python.org>
parents:
4542
diff
changeset
|
1689 |
|
e52054440efc
Added os.remove()/unlink(), rmdir(), rename(), and [f]truncate().
Guido van Rossum <guido@python.org>
parents:
4542
diff
changeset
|
1690 To rename a file, use os.rename(). |
|
e52054440efc
Added os.remove()/unlink(), rmdir(), rename(), and [f]truncate().
Guido van Rossum <guido@python.org>
parents:
4542
diff
changeset
|
1691 |
|
e52054440efc
Added os.remove()/unlink(), rmdir(), rename(), and [f]truncate().
Guido van Rossum <guido@python.org>
parents:
4542
diff
changeset
|
1692 To truncate a file, open it using f = open(filename, "w+"), and use |
|
e52054440efc
Added os.remove()/unlink(), rmdir(), rename(), and [f]truncate().
Guido van Rossum <guido@python.org>
parents:
4542
diff
changeset
|
1693 f.truncate(offset); offset defaults to the current seek position. |
|
e52054440efc
Added os.remove()/unlink(), rmdir(), rename(), and [f]truncate().
Guido van Rossum <guido@python.org>
parents:
4542
diff
changeset
|
1694 There's also os.ftruncate(fd, offset) for files opened with os.open() |
|
e52054440efc
Added os.remove()/unlink(), rmdir(), rename(), and [f]truncate().
Guido van Rossum <guido@python.org>
parents:
4542
diff
changeset
|
1695 -- for advanced Unix hacks only. |
|
e52054440efc
Added os.remove()/unlink(), rmdir(), rename(), and [f]truncate().
Guido van Rossum <guido@python.org>
parents:
4542
diff
changeset
|
1696 |
|
5200
024e738674a5
Added Q. about HTTP/1.1.
Guido van Rossum <guido@python.org>
parents:
5157
diff
changeset
|
1697 4.42. Q. How to modify urllib or httplib to support HTTP/1.1? |
|
024e738674a5
Added Q. about HTTP/1.1.
Guido van Rossum <guido@python.org>
parents:
5157
diff
changeset
|
1698 |
|
024e738674a5
Added Q. about HTTP/1.1.
Guido van Rossum <guido@python.org>
parents:
5157
diff
changeset
|
1699 A. Apply the following patch to httplib.py: |
|
024e738674a5
Added Q. about HTTP/1.1.
Guido van Rossum <guido@python.org>
parents:
5157
diff
changeset
|
1700 |
|
024e738674a5
Added Q. about HTTP/1.1.
Guido van Rossum <guido@python.org>
parents:
5157
diff
changeset
|
1701 41c41 |
|
024e738674a5
Added Q. about HTTP/1.1.
Guido van Rossum <guido@python.org>
parents:
5157
diff
changeset
|
1702 < replypat = regsub.gsub('\\.', '\\\\.', HTTP_VERSION) + \ |
|
024e738674a5
Added Q. about HTTP/1.1.
Guido van Rossum <guido@python.org>
parents:
5157
diff
changeset
|
1703 --- |
|
024e738674a5
Added Q. about HTTP/1.1.
Guido van Rossum <guido@python.org>
parents:
5157
diff
changeset
|
1704 > replypat = regsub.gsub('\\.', '\\\\.', 'HTTP/1.[0-9]+') + \ |
|
024e738674a5
Added Q. about HTTP/1.1.
Guido van Rossum <guido@python.org>
parents:
5157
diff
changeset
|
1705 |
|
5201
5878a5af3148
Added note about adding \n to source for exec and compile.
Guido van Rossum <guido@python.org>
parents:
5200
diff
changeset
|
1706 4.43. Q. Unexplicable syntax errors in compile() or exec. |
|
5878a5af3148
Added note about adding \n to source for exec and compile.
Guido van Rossum <guido@python.org>
parents:
5200
diff
changeset
|
1707 |
|
5878a5af3148
Added note about adding \n to source for exec and compile.
Guido van Rossum <guido@python.org>
parents:
5200
diff
changeset
|
1708 A. When a statement suite (as opposed to an expression) is compiled by |
|
5878a5af3148
Added note about adding \n to source for exec and compile.
Guido van Rossum <guido@python.org>
parents:
5200
diff
changeset
|
1709 compile(), exec or execfile(), it *must* end in a newline. In some |
|
5878a5af3148
Added note about adding \n to source for exec and compile.
Guido van Rossum <guido@python.org>
parents:
5200
diff
changeset
|
1710 cases, when the source ends in an indented block it appears that at |
|
5878a5af3148
Added note about adding \n to source for exec and compile.
Guido van Rossum <guido@python.org>
parents:
5200
diff
changeset
|
1711 least two newlines are required. |
|
5200
024e738674a5
Added Q. about HTTP/1.1.
Guido van Rossum <guido@python.org>
parents:
5157
diff
changeset
|
1712 |
|
5215
f70042c19c57
Added two new questions about number conversions.
Guido van Rossum <guido@python.org>
parents:
5201
diff
changeset
|
1713 4.44. Q. How do I convert a string to a number? |
|
f70042c19c57
Added two new questions about number conversions.
Guido van Rossum <guido@python.org>
parents:
5201
diff
changeset
|
1714 |
|
f70042c19c57
Added two new questions about number conversions.
Guido van Rossum <guido@python.org>
parents:
5201
diff
changeset
|
1715 A. To convert, e.g., the string '144' to the number 144, import the |
|
f70042c19c57
Added two new questions about number conversions.
Guido van Rossum <guido@python.org>
parents:
5201
diff
changeset
|
1716 module string and use the string.atoi() function. For floating point |
|
f70042c19c57
Added two new questions about number conversions.
Guido van Rossum <guido@python.org>
parents:
5201
diff
changeset
|
1717 numbers, use string.atof(); for long integers, use string.atol(). See |
|
f70042c19c57
Added two new questions about number conversions.
Guido van Rossum <guido@python.org>
parents:
5201
diff
changeset
|
1718 the library reference manual section for the string module for more |
|
f70042c19c57
Added two new questions about number conversions.
Guido van Rossum <guido@python.org>
parents:
5201
diff
changeset
|
1719 details. While you could use the built-in function eval() instead of |
|
f70042c19c57
Added two new questions about number conversions.
Guido van Rossum <guido@python.org>
parents:
5201
diff
changeset
|
1720 any of those, this is not recommended, because someone could pass you |
|
f70042c19c57
Added two new questions about number conversions.
Guido van Rossum <guido@python.org>
parents:
5201
diff
changeset
|
1721 a Python expression that might have unwanted side effects (like |
|
f70042c19c57
Added two new questions about number conversions.
Guido van Rossum <guido@python.org>
parents:
5201
diff
changeset
|
1722 reformatting your disk). |
|
f70042c19c57
Added two new questions about number conversions.
Guido van Rossum <guido@python.org>
parents:
5201
diff
changeset
|
1723 |
|
f70042c19c57
Added two new questions about number conversions.
Guido van Rossum <guido@python.org>
parents:
5201
diff
changeset
|
1724 4.45. Q. How do I convert a number to a string? |
|
f70042c19c57
Added two new questions about number conversions.
Guido van Rossum <guido@python.org>
parents:
5201
diff
changeset
|
1725 |
|
f70042c19c57
Added two new questions about number conversions.
Guido van Rossum <guido@python.org>
parents:
5201
diff
changeset
|
1726 A. To convert, e.g., the number 144 to the string '144', use the |
|
f70042c19c57
Added two new questions about number conversions.
Guido van Rossum <guido@python.org>
parents:
5201
diff
changeset
|
1727 built-in function repr() or the backquote notation (these are |
|
f70042c19c57
Added two new questions about number conversions.
Guido van Rossum <guido@python.org>
parents:
5201
diff
changeset
|
1728 equivalent). If you want a hexadecimal or octal representation, use |
|
f70042c19c57
Added two new questions about number conversions.
Guido van Rossum <guido@python.org>
parents:
5201
diff
changeset
|
1729 the built-in functions hex() or oct(), respectively. For fancy |
|
f70042c19c57
Added two new questions about number conversions.
Guido van Rossum <guido@python.org>
parents:
5201
diff
changeset
|
1730 formatting, use the % operator on strings, just like C printf formats, |
|
f70042c19c57
Added two new questions about number conversions.
Guido van Rossum <guido@python.org>
parents:
5201
diff
changeset
|
1731 e.g. "%04d" % 144 yields '0144' and "%.3f" % (1/3.0) yields '0.333'. |
|
f70042c19c57
Added two new questions about number conversions.
Guido van Rossum <guido@python.org>
parents:
5201
diff
changeset
|
1732 See the library reference manual for details. |
|
f70042c19c57
Added two new questions about number conversions.
Guido van Rossum <guido@python.org>
parents:
5201
diff
changeset
|
1733 |
| 1942 | 1734 |
| 1529 | 1735 5. Extending Python |
| 1736 =================== | |
| 1737 | |
| 1738 5.1. Q. Can I create my own functions in C? | |
| 1739 | |
| 1740 A. Yes, you can create built-in modules containing functions, | |
|
1541
630e03109c63
Released version 1.4; out after 1.0.0 is released...
Guido van Rossum <guido@python.org>
parents:
1535
diff
changeset
|
1741 variables, exceptions and even new types in C. This is explained in |
|
630e03109c63
Released version 1.4; out after 1.0.0 is released...
Guido van Rossum <guido@python.org>
parents:
1535
diff
changeset
|
1742 the document "Extending and Embedding the Python Interpreter" (the |
|
630e03109c63
Released version 1.4; out after 1.0.0 is released...
Guido van Rossum <guido@python.org>
parents:
1535
diff
changeset
|
1743 LaTeX file Doc/ext.tex). Also read the chapter on dynamic loading. |
| 1529 | 1744 |
| 1745 5.2. Q. Can I create my own functions in C++? | |
| 1746 | |
| 1747 A. Yes, using the C-compatibility features found in C++. Basically | |
| 1748 you place extern "C" { ... } around the Python include files and put | |
| 1749 extern "C" before each function that is going to be called by the | |
| 1750 Python interpreter. Global or static C++ objects with constructors | |
| 1751 are probably not a good idea. | |
| 1752 | |
| 1663 | 1753 5.3. Q. How can I execute arbitrary Python statements from C? |
| 1754 | |
| 1755 A. The highest-level function to do this is run_command() which takes | |
| 1756 a single string argument which is executed in the context of module | |
| 1757 __main__ and returns 0 for success and -1 when an exception occurred | |
| 1758 (including SyntaxError). If you want more control, use run_string(); | |
| 1759 see the source for run_command() in Python/pythonrun.c. | |
| 1760 | |
| 1761 5.4. Q. How can I evaluate an arbitrary Python expression from C? | |
| 1762 | |
| 1763 A. Call the function run_string() from the previous question with the | |
| 1764 start symbol eval_input; it then parses an expression, evaluates it | |
| 1765 and returns its value. See exec_eval() in Python/bltinmodule.c. | |
| 1766 | |
| 1767 5.5. Q. How do I extract C values from a Python object? | |
| 1768 | |
| 1769 A. That depends on the object's type. If it's a tuple, | |
| 1770 gettuplesize(o) returns its length and gettupleitem(o, i) returns its | |
| 1771 i'th item; similar for lists with getlistsize(o) and getlistitem(o, | |
| 1772 i). For strings, getstringsize(o) returns its length and | |
| 1773 getstringvalue(o) a pointer to its value (note that Python strings may | |
| 1774 contain null bytes so strlen() is not safe). To test which type an | |
| 1775 object is, first make sure it isn't NULL, and then use | |
| 1776 is_stringobject(o), is_tupleobject(o), is_listobject(o) etc. | |
| 1777 | |
| 1778 5.6. Q. How do I use mkvalue() to create a tuple of arbitrary length? | |
| 1779 | |
| 1780 A. You can't. Use t = newtupleobject(n) instead, and fill it with | |
| 1781 objects using settupleitem(t, i, o) -- note that this "eats" a | |
| 1782 reference count of o. Similar for lists with newlistobject(n) and | |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1783 setlistitem(l, i, o). Note that you *must* set all the tuple items to |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1784 some value before you pass the tuple to Python code -- |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1785 newtupleobject(n) initializes them to NULL, which isn't a valid Python |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1786 value. |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1787 |
|
4250
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
1788 5.7. Q. How do I call an object's method from C? |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1789 |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1790 A. Here's a function (untested) that might become part of the next |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1791 release in some form. It uses <stdarg.h> to allow passing the |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1792 argument list on to vmkvalue(): |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1793 |
| 2048 | 1794 object *call_method(object *inst, char *methodname, char *format, ...) |
| 1795 { | |
| 1796 object *method; | |
| 1797 object *args; | |
| 1798 object *result; | |
| 1799 va_list va; | |
| 1800 method = getattr(inst, methodname); | |
| 1801 if (method == NULL) return NULL; | |
| 1802 va_start(va, format); | |
| 1803 args = vmkvalue(format, va); | |
| 1804 va_end(va); | |
| 1805 if (args == NULL) { | |
| 1806 DECREF(method); | |
| 1807 return NULL; | |
| 1808 } | |
| 1809 result = call_object(method, args); | |
| 1810 DECREF(method); | |
| 1811 DECREF(args); | |
| 1812 return result; | |
| 1813 } | |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1814 |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1815 This works for any instance that has methods -- whether built-in or |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1816 user-defined. You are responsible for eventually DECREF'ing the |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1817 return value. |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1818 |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1819 To call, e.g., a file object's "seek" method with arguments 10, 0 |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1820 (assuming the file object pointer is "f"): |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1821 |
| 2048 | 1822 res = call_method(f, "seek", "(OO)", 10, 0); |
| 1823 if (res == NULL) { | |
| 1824 ... an exception occurred ... | |
| 1825 } | |
| 1826 else { | |
| 1827 DECREF(res); | |
| 1828 } | |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1829 |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1830 Note that since call_object() *always* wants a tuple for the argument |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1831 list, to call a function without arguments, pass "()" for the format, |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1832 and to call a function with one argument, surround the argument in |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1833 parentheses, e.g. "(i)". |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1834 |
|
4250
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
1835 5.8. Q. How do I catch the output from print_error()? |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1836 |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1837 A. (Due to Mark Hammond): |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1838 |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1839 * in Python code, define an object that supports the "write()" method. |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1840 |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1841 * redirect sys.stdout and sys.stderr to this object. |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1842 |
| 1942 | 1843 * call print_error, or just allow the standard traceback mechanism to |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1844 work. |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1845 |
| 1942 | 1846 Then, the output will go wherever your write() method sends it. |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1847 |
|
4250
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
1848 5.9. Q. How do I access a module written in Python from C? |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1849 |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1850 A. You can get a pointer to the module object as follows: |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1851 |
| 2048 | 1852 module = import_module("<modulename>"); |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1853 |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1854 If the module hasn't been imported yet (i.e. it is not yet present in |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1855 sys.modules), this initializes the module; otherwise it simply returns |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1856 the value of sys.modules["<modulename>"]. Note that it doesn't enter |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1857 the module into any namespace -- it only ensures it has been |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1858 initialized and is stored in sys.modules. |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1859 |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1860 You can then access the module's attributes (i.e. any name defined in |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1861 the module) as follows: |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1862 |
| 2048 | 1863 attr = getattr(module, "<attrname>"); |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1864 |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
1865 Calling setattr(), to assign to variables in the module, also works. |
| 1663 | 1866 |
|
4250
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
1867 5.10. Q. How do I interface to C++ objects from Python? |
|
3023
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
1868 |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
1869 A. Depending on your requirements, there are many approaches. Begin |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
1870 by reading the "Extending and Embedding" document (Doc/ext.tex, see |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
1871 also <URL:http://www.python.org/doc/>). Realize that for the Python |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
1872 run-time system, there isn't a whole lot of difference between C and |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
1873 C++ -- so the strategy to build a new Python type around a C structure |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
1874 (pointer) type will also work for C++ objects. |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
1875 |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
1876 Automatic generation of interfaces between Python and C++ is still at |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
1877 the horizon -- parsing C++ header files requires an almost complete |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
1878 C++ parser, and many features aren't easily translated from C++ to |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
1879 Python: certain forms of operator oveloading, function overloading |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
1880 (best approached by a varargs function which explicitly type-checks |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
1881 its arguments), and reference arguments are just a number of features |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
1882 that are hard to translate correctly if at all. |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
1883 |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
1884 The hardest problem is to transparently translate the C++ class |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
1885 hierarchy to Python, so that Python programs derive classes from C++ |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
1886 classes. Given suitable constraints, this may be possible, but it |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
1887 would require more space than I have in this FAQ to explain how. |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
1888 In any case, you can get quite a bit done without this, using just the |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
1889 existing classes from Python. |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
1890 |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
1891 If this all seems rather daunting, that may be because it is -- C++ |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
1892 isn't exactly a baby to handle without gloves! However, people have |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
1893 accomplished amazing feats of interfacing between Python and C++, and |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
1894 a detailed question posted to the Python list is likely to elicit some |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
1895 interesting and useful responses. |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
1896 |
| 1529 | 1897 |
| 1898 6. Python's design | |
| 1899 ================== | |
| 1900 | |
|
4250
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
1901 6.1. Q. Why isn't there a switch or case statement in Python? |
| 1529 | 1902 |
| 1903 A. You can do this easily enough with a sequence of | |
| 1904 if... elif... elif... else. There have been some proposals for switch | |
| 1942 | 1905 statement syntax, but there is no consensus (yet) on whether and how |
| 1529 | 1906 to do range tests. |
| 1907 | |
|
4250
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
1908 6.2. Q. Why does Python use indentation for grouping of statements? |
|
1657
f02a46754f50
Added stuff about indentation
Guido van Rossum <guido@python.org>
parents:
1613
diff
changeset
|
1909 |
|
f02a46754f50
Added stuff about indentation
Guido van Rossum <guido@python.org>
parents:
1613
diff
changeset
|
1910 A. Basically I believe that using indentation for grouping is |
|
f02a46754f50
Added stuff about indentation
Guido van Rossum <guido@python.org>
parents:
1613
diff
changeset
|
1911 extremely elegant and contributes a lot to the clarity of the average |
|
f02a46754f50
Added stuff about indentation
Guido van Rossum <guido@python.org>
parents:
1613
diff
changeset
|
1912 Python program. Most people learn to love this feature after a while. |
|
f02a46754f50
Added stuff about indentation
Guido van Rossum <guido@python.org>
parents:
1613
diff
changeset
|
1913 Some arguments for it: |
|
f02a46754f50
Added stuff about indentation
Guido van Rossum <guido@python.org>
parents:
1613
diff
changeset
|
1914 |
|
f02a46754f50
Added stuff about indentation
Guido van Rossum <guido@python.org>
parents:
1613
diff
changeset
|
1915 - Since there are no begin/end brackets there cannot be a disagreement |
|
f02a46754f50
Added stuff about indentation
Guido van Rossum <guido@python.org>
parents:
1613
diff
changeset
|
1916 between grouping perceived by the parser and the human reader. I |
|
f02a46754f50
Added stuff about indentation
Guido van Rossum <guido@python.org>
parents:
1613
diff
changeset
|
1917 remember long ago seeing a C fragment like this: |
|
f02a46754f50
Added stuff about indentation
Guido van Rossum <guido@python.org>
parents:
1613
diff
changeset
|
1918 |
| 2048 | 1919 if (x <= y) |
| 1920 x++; | |
| 1921 y--; | |
| 1922 z++; | |
|
1657
f02a46754f50
Added stuff about indentation
Guido van Rossum <guido@python.org>
parents:
1613
diff
changeset
|
1923 |
|
f02a46754f50
Added stuff about indentation
Guido van Rossum <guido@python.org>
parents:
1613
diff
changeset
|
1924 and staring a long time at it wondering why y was being decremented |
|
f02a46754f50
Added stuff about indentation
Guido van Rossum <guido@python.org>
parents:
1613
diff
changeset
|
1925 even for x > y... (And I wasn't a C newbie then either.) |
|
f02a46754f50
Added stuff about indentation
Guido van Rossum <guido@python.org>
parents:
1613
diff
changeset
|
1926 |
|
2716
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
1927 - Since there are no begin/end brackets, Python is much less prone to |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
1928 coding-style conflicts. In C there are loads of different ways to |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
1929 place the braces (including the choice whether to place braces around |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
1930 single statements in certain cases, for consistency). If you're used |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
1931 to reading (and writing) code that uses one style, you will feel at |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
1932 least slightly uneasy when reading (or being required to write) |
|
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
1933 another style. |
|
1657
f02a46754f50
Added stuff about indentation
Guido van Rossum <guido@python.org>
parents:
1613
diff
changeset
|
1934 |
|
f02a46754f50
Added stuff about indentation
Guido van Rossum <guido@python.org>
parents:
1613
diff
changeset
|
1935 - Many coding styles place begin/end brackets on a line by themself. |
|
f02a46754f50
Added stuff about indentation
Guido van Rossum <guido@python.org>
parents:
1613
diff
changeset
|
1936 This makes programs considerably longer and wastes valuable screen |
|
f02a46754f50
Added stuff about indentation
Guido van Rossum <guido@python.org>
parents:
1613
diff
changeset
|
1937 space, making it harder to get a good overview over a program. |
|
f02a46754f50
Added stuff about indentation
Guido van Rossum <guido@python.org>
parents:
1613
diff
changeset
|
1938 Ideally, a function should fit on one basic tty screen (say, 20 |
|
f02a46754f50
Added stuff about indentation
Guido van Rossum <guido@python.org>
parents:
1613
diff
changeset
|
1939 lines). 20 lines of Python are worth a LOT more than 20 lines of C. |
|
f02a46754f50
Added stuff about indentation
Guido van Rossum <guido@python.org>
parents:
1613
diff
changeset
|
1940 This is not solely due to the lack of begin/end brackets (the lack of |
|
f02a46754f50
Added stuff about indentation
Guido van Rossum <guido@python.org>
parents:
1613
diff
changeset
|
1941 declarations also helps, and the powerful operations of course), but |
|
f02a46754f50
Added stuff about indentation
Guido van Rossum <guido@python.org>
parents:
1613
diff
changeset
|
1942 it certainly helps! |
|
f02a46754f50
Added stuff about indentation
Guido van Rossum <guido@python.org>
parents:
1613
diff
changeset
|
1943 |
|
4250
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
1944 6.3. Q. Why are Python strings immutable? |
|
1740
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
1945 |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
1946 A. There are two advantages. One is performance: knowing that a |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
1947 string is immutable makes it easy to lay it out at construction time |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
1948 -- fixed and unchanging storage requirements. (This is also one of |
| 1942 | 1949 the reasons for the distinction between tuples and lists.) The |
|
1740
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
1950 other is that strings in Python are considered as "elemental" as |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
1951 numbers. No amount of activity will change the value 8 to anything |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
1952 else, and in Python, no amount of activity will change the string |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
1953 "eight" to anything else. (Adapted from Jim Roskind) |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
1954 |
|
4250
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
1955 6.4. Q. Why don't strings have methods like index() or sort(), like |
|
1740
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
1956 lists? |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
1957 |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
1958 A. Good question. Strings currently don't have methods at all |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
1959 (likewise tuples and numbers). Long ago, it seemed unnecessary to |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
1960 implement any of these functions in C, so a standard library module |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
1961 "string" written in Python was created that performs string related |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
1962 operations. Since then, the cry for performance has moved most of |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
1963 them into the built-in module strop (this is imported by module |
|
1784
a3f199e8bac6
1.12 -- new address for fu-berlin mirror, infoseek uses python, more
Guido van Rossum <guido@python.org>
parents:
1740
diff
changeset
|
1964 string, which is still the preferred interface, without loss of |
|
1740
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
1965 performance except during initialization). Some of these functions |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
1966 (e.g. index()) could easily be implemented as string methods instead, |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
1967 but others (e.g. sort()) can't, since their interface prescribes that |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
1968 they modify the object, while strings are immutable (see the previous |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
1969 question). |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
1970 |
|
4250
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
1971 6.5. Q. Why does Python use methods for some functionality |
|
1740
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
1972 (e.g. list.index()) but functions for other (e.g. len(list))? |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
1973 |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
1974 A. Functions are used for those operations that are generic for a |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
1975 group of types and which should work even for objects that don't have |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
1976 methods at all (e.g. numbers, strings, tuples). Also, implementing |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
1977 len(), max(), min() as a built-in function is actually less code than |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
1978 implementing them as methods for each type. One can quibble about |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
1979 individual cases but it's really too late to change such things |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
1980 fundamentally now. |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
1981 |
|
4250
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
1982 6.6. Q. Why can't I derive a class from built-in types (e.g. lists or |
|
1740
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
1983 files)? |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
1984 |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
1985 A. This is caused by the relatively late addition of (user-defined) |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
1986 classes to the language -- the implementation framework doesn't easily |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
1987 allow it. See the answer to question 4.2 for a work-around. This |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
1988 *may* be fixed in the (distant) future. |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
1989 |
|
4250
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
1990 6.7. Q. Why must 'self' be declared and used explicitly in method |
|
1740
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
1991 definitions and calls? |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
1992 |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
1993 A. By asking this question you reveal your C++ background. :-) |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
1994 When I added classes, this was (again) the simplest way of |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
1995 implementing methods without too many changes to the interpreter. I |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
1996 borrowed the idea from Modula-3. It turns out to be very useful, for |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
1997 a variety of reasons. |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
1998 |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
1999 First, it makes it more obvious that you are using a method or |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
2000 instance attribute instead of a local variable. Reading "self.x" or |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
2001 "self.meth()" makes it absolutely clear that an instance variable or |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
2002 method is used even if you don't know the class definition by heart. |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
2003 In C++, you can sort of tell by the lack of a local variable |
| 1942 | 2004 declaration (assuming globals are rare or easily recognizable) -- but |
|
1740
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
2005 in Python, there are no local variable declarations, so you'd have to |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
2006 look up the class definition to be sure. |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
2007 |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
2008 Second, it means that no special syntax is necessary if you want to |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
2009 explicitly reference or call the method from a particular class. In |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
2010 C++, if you want to use a method from base class that is overridden in |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
2011 a derived class, you have to use the :: operator -- in Python you can |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
2012 write baseclass.methodname(self, <argument list>). This is |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
2013 particularly useful for __init__() methods, and in general in cases |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
2014 where a derived class method wants to extend the base class method of |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
2015 the same name and thus has to call the base class method somehow. |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
2016 |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
2017 Lastly, for instance variables, it solves a syntactic problem with |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
2018 assignment: since local variables in Python are (by definition!) those |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
2019 variables to which a value assigned in a function body (and that |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
2020 aren't explicitly declared global), there has to be some way to tell |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
2021 the interpreter that an assignment was meant to assign to an instance |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
2022 variable instead of to a local variable, and it should preferably be |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
2023 syntactic (for efficiency reasons). C++ does this through |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
2024 declarations, but Python doesn't have declarations and it would be a |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
2025 pity having to introduce them just for this purpose. Using the |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
2026 explicit "self.var" solves this nicely. Similarly, for using instance |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
2027 variables, having to write "self.var" means that references to |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
2028 unqualified names inside a method don't have to search the instance's |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
2029 directories. |
|
e95b0701c8b5
Version 1.11 -- added several new answers on design questions
Guido van Rossum <guido@python.org>
parents:
1735
diff
changeset
|
2030 |
|
4250
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
2031 6.8. Q. Can't you emulate threads in the interpreter instead of |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
2032 relying on an OS-specific thread implementation? |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
2033 |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
2034 A. Unfortunately, the interpreter pushes at least one C stack frame |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
2035 for each Python stack frame. Also, extensions can call back into |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
2036 Python at almost random moments. Therefore a complete threads |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
2037 implementation requires thread support for C. |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
2038 |
|
4250
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
2039 6.9. Q. Why can't lambda forms contain statements? |
| 1942 | 2040 |
| 2041 A. Python lambda forms cannot contain statements because Python's | |
|
2208
c68a0113b75a
intermediate version -- why not...
Guido van Rossum <guido@python.org>
parents:
2048
diff
changeset
|
2042 syntactic framework can't handle statements nested inside expressions. |
| 1942 | 2043 |
| 2044 However, in Python, this is not a serious problem. Unlike lambda | |
| 2045 forms in other languages, where they add functionality, Python lambdas | |
| 2046 are only a shorthand notation if you're too lazy to define a function. | |
| 2047 | |
| 2048 Functions are already first class objects in Python, and can be | |
| 2049 declared in a local scope. Therefore the only advantage of using a | |
| 2050 lambda form instead of a locally-defined function is that you'll have | |
| 2051 to invent a name for the function -- but that's just a local variable | |
| 2052 to which the function object (which is exactly the same type of object | |
| 2053 that a lambda form yields) is assigned! | |
| 2054 | |
|
4250
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
2055 6.10. Q. Why don't lambdas have access to variables defined in the |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
2056 containing scope? |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
2057 |
|
4278
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
2058 A. Because they are implemented as ordinary functions. |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
2059 See question 4.5 above. |
|
4250
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
2060 |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
2061 6.11. Q. Why can't recursive functions be defined inside other functions? |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
2062 |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
2063 A. See question 4.5 above. |
|
4470f7ff0c23
Removed some obsolete questions and references to version 1.2.
Guido van Rossum <guido@python.org>
parents:
4221
diff
changeset
|
2064 |
| 1942 | 2065 6.12. Q. Why is there no more efficient way of iterating over a dictionary |
| 2066 than first constructing the list of keys()? | |
| 2067 | |
| 2068 A. Have you tried it? I bet it's fast enough for your purposes! In | |
| 2069 most cases such a list takes only a few percent of the space occupied | |
| 2070 by the dictionary -- it needs only 4 bytes (the size of a pointer) per | |
| 2071 key -- a dictionary costs 8 bytes per key plus between 30 and 70 | |
| 2072 percent hash table overhead, plus the space for the keys and values -- | |
| 2073 by necessity all keys are unique objects and a string object (the most | |
| 2074 common key type) costs at least 18 bytes plus the length of the | |
| 2075 string. Add to that the values contained in the dictionary, and you | |
| 2076 see that 4 bytes more per item really isn't that much more memory... | |
| 2077 | |
| 2078 A call to dict.keys() makes one fast scan over the dictionary | |
| 2079 (internally, the iteration function does exist) copying the pointers | |
| 2080 to the key objects into a pre-allocated list object of the right size. | |
| 2081 The iteration time isn't lost (since you'll have to iterate anyway -- | |
| 2082 unless in the majority of cases your loop terminates very prematurely | |
| 2083 (which I doubt since you're getting the keys in random order). | |
| 2084 | |
| 2085 I don't expose the dictionary iteration operation to Python | |
| 2086 programmers because the dictionary shouldn't be modified during the | |
| 2087 entire iteration -- if it is, there's a very small chance that the | |
| 2088 dictionary is reorganized because the hash table becomes too full, and | |
| 2089 then the iteration may miss some items and see others twice. Exactly | |
| 2090 because this only occurs rarely, it would lead to hidden bugs in | |
| 2091 programs: it's easy never to have it happen during test runs if you | |
| 2092 only insert or delete a few items per iteration -- but your users will | |
| 2093 surely hit upon it sooner or later. | |
| 2094 | |
|
3023
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
2095 6.13. Q. Can Python be compiled to machine code, C or some other language? |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
2096 |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
2097 A. Not easily. Python's high level data types, dynamic typing of |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
2098 objects and run-time invocation of the interpreter (using eval() or |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
2099 exec) together mean that a "compiled" Python program would probably |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
2100 consist mostly of calls into the Python run-time system, even for |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
2101 seemingly simple operations like "x+1". Thus, the performance gain |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
2102 would probably be minimal. |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
2103 |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
2104 Internally, Python source code is always translated into a "virtual |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
2105 machine code" or "byte code" representation before it is interpreted |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
2106 (by the "Python virtual machine" or "bytecode interpreter"). In order |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
2107 to avoid the overhead of parsing and translating modules that rarely |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
2108 change over and over again, this byte code is written on a file whose |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
2109 name ends in ".pyc" whenever a module is parsed (from a file whose |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
2110 name ends in ".py"). When the corresponding .py file is changed, it |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
2111 is parsed and translated again and the .pyc file is rewritten. There |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
2112 is no performance difference once the .pyc file has been loaded (the |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
2113 bytecode read from the .pyc file is exactly the same as the bytecode |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
2114 created by direct translation). The only difference is that loading |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
2115 code from a .pyc file is faster than parsing and translating a .py |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
2116 file, so the presence of precompiled .pyc files will generally improve |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
2117 start-up time of Python scripts. If desired, the Lib/compileall.py |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
2118 module/script can be used to force creation of valid .pyc files for a |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
2119 given set of modules. |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
2120 |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
2121 If you are looking for a way to translate Python programs in order to |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
2122 distribute them in binary form, without the need to distribute the |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
2123 interpreter and library as well, have a look at the freeze.py script |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
2124 in the Tools/freeze directory. This creates a single binary file |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
2125 incorporating your program, the Python interpreter, and those parts of |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
2126 the Python library that are needed by your program. Of course, the |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
2127 resulting binary will only run on the same type of platform as that |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
2128 used to create it. |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
2129 |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
2130 Hints for proper usage of freeze.py: |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
2131 |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
2132 - the script must be in a file whose name ends in .py |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
2133 |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
2134 - you must have installed Python fully: |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
2135 |
|
3207
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
2136 make install |
|
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
2137 make libinstall |
|
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
2138 make inclinstall |
|
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
2139 make libainstall |
|
3023
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
2140 |
|
3126
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
2141 6.14. Q. Why doesn't Python use proper garbage collection? |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
2142 |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
2143 A. It's looking less and less likely that Python will ever get |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
2144 "automatic" garbage collection (GC). For one thing, unless this were |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
2145 added to C as a standard feature, it's a portability pain in the ass. |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
2146 And yes, I know about the Xerox library. It has bits of assembler |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
2147 code for *most* *common* platforms. Not for all. And although it is |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
2148 mostly transparent, it isn't completely transparent (when I once |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
2149 linked Python with it, it dumped core). |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
2150 |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
2151 "Proper" GC also becomes a problem when Python gets embedded into |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
2152 other applications. While in a stand-alone Python it may be fine to |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
2153 replace the standard malloc() and free() with versions provided by the |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
2154 GC library, an application embedding Python may want to have its *own* |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
2155 substitute for malloc() and free(), and may not want Python's. Right |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
2156 now, Python works with anything that implements malloc() and free() |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
2157 properly. |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
2158 |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
2159 Besides, the predictability of destructor calls in Python is kind of |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
2160 attractive. With GC, the following code (which is fine in current |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
2161 Python) will run out of file descriptors long before it runs out of |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
2162 memory: |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
2163 |
|
3207
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
2164 for file in <very long list of files>: |
|
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
2165 f = open(file) |
|
0ed5cd8df51f
all sorts of minor nits
Guido van Rossum <guido@python.org>
parents:
3126
diff
changeset
|
2166 c = file.read(1) |
|
3126
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
2167 |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
2168 Using the current reference counting and destructor scheme, each new |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
2169 assignment to f closes the previous file. Using GC, this is not |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
2170 guaranteed. Sure, you can think of ways to fix this. But it's not |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
2171 off-the-shelf technology. |
|
e90643f33c64
+aaron watters, +PSA, +GC, -lance, -beta
Guido van Rossum <guido@python.org>
parents:
3023
diff
changeset
|
2172 |
| 1529 | 2173 |
| 2174 7. Using Python on non-UNIX platforms | |
| 2175 ===================================== | |
| 2176 | |
|
1547
0efa240b1dbc
At the release of 1.0.1
Guido van Rossum <guido@python.org>
parents:
1541
diff
changeset
|
2177 7.1. Q. Is there a Mac version of Python? |
| 1529 | 2178 |
|
2661
b4fd48e3a3b8
changed path references
Guido van Rossum <guido@python.org>
parents:
2660
diff
changeset
|
2179 A. Yes, see the "mac" subdirectory of the distribution sites, |
|
2716
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
2180 e.g. <URL:ftp://ftp.python.org/pub/python/mac/>. |
|
1547
0efa240b1dbc
At the release of 1.0.1
Guido van Rossum <guido@python.org>
parents:
1541
diff
changeset
|
2181 |
|
4278
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
2182 7.2. Q. Are there DOS and Windows versions of Python? |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
2183 |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
2184 A. Yes. There is a plethora of not-always-compatible versions. See |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
2185 the "pythonwin", "wpy", "nt" and "pc" subdirectories of the |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
2186 distribution sites. A quick comparison: |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
2187 |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
2188 PythonWin: Extensive support for the 32-bit native Windows API and GUI |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
2189 building using MFC. Windows NT and Windows 95 only (and Windows |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
2190 3.1(1) using win32s, until Microsoft stops supporting it :-( ). |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
2191 <URL:ftp://ftp.python.org/pub/python/pythonwin/>. |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
2192 |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
2193 WPY: Ports to DOS, Windows 3.1(1), Windows 95, Windows NT and OS/2. |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
2194 Also contains a GUI package that offers portability between Windows |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
2195 (not DOS) and Unix, and native look and feel on both. |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
2196 <URL:ftp://ftp.python.org/pub/python/wpy/>. |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
2197 |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
2198 NT: Basic ports built straight from the 1.4 distribution for Windows |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
2199 95 and Windows NT. This will eventually provide core support for |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
2200 both PythonWin and WPY on all 32-bit Microsoft platforms. |
| 2855 | 2201 <URL:ftp://ftp.python.org/pub/python/nt/>. |
| 2202 | |
|
4278
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
2203 PC: Old, unsupported ports to DOS, Windows 3.1(1) and OS/2. |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
2204 <URL:ftp://ftp.python.org/pub/python/pc/>. |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
2205 |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
2206 7.3. Q. Is there an OS/2 version of Python? |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
2207 |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
2208 A. Yes, see the "pc" and "wpy" subdirectory of the distribution sites |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
2209 (see above). |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
2210 |
|
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
2211 7.4. Q. Is there a VMS version of Python? |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
2212 |
| 2855 | 2213 A. Donn Cave <donn@cac.washington.edu> did a partial port. The |
| 2214 results of his efforts are on public display in | |
| 3018 | 2215 <<URL:ftp://ftp.python.org/pub/python/contrib/vms.tar.gz/>. Someone |
| 2216 else is working on a more complete port, for details watch the list. | |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
2217 |
|
4278
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
2218 7.5. Q. What about IBM mainframes, or other non-UNIX platforms? |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
2219 |
|
3023
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
2220 A. I haven't heard about these, except I remember hearing about an |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
2221 OS/9 port and a port to Vxworks (both operating systems for embedded |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
2222 systems). If you're interested in any of this, go directly to the |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
2223 newsgroup and ask there, you may find exactly what you need. For |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
2224 example, a port to MPE/iX 5.0 on HP3000 computers was just announced, |
|
87847228b158
several new questions, 1.3 beta mentioned
Guido van Rossum <guido@python.org>
parents:
3018
diff
changeset
|
2225 see <URL:http://www.allegro.com/software/>. |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
2226 |
|
4278
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
2227 7.6. Q. Where are the source or Makefiles for the non-UNIX versions? |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
2228 |
|
2661
b4fd48e3a3b8
changed path references
Guido van Rossum <guido@python.org>
parents:
2660
diff
changeset
|
2229 A. The standard sources can (almost) be used. Additional sources can |
|
b4fd48e3a3b8
changed path references
Guido van Rossum <guido@python.org>
parents:
2660
diff
changeset
|
2230 be found in the platform-specific subdirectories of the distribution. |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
2231 |
|
4278
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
2232 7.7. Q. What is the status and support for the non-UNIX versions? |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
2233 |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
2234 A. I don't have access to most of these platforms, so in general I am |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
2235 dependent on material submitted by volunteers(*). However I strive to |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
2236 integrate all changes needed to get it to compile on a particular |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
2237 platform back into the standard sources, so porting of the next |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
2238 version to the various non-UNIX platforms should be easy. |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
2239 |
| 2048 | 2240 (*) For the Macintosh, that volunteer is me, with help from Jack |
| 2241 Jansen <jack@cwi.nl>. | |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
2242 |
|
4278
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
2243 7.8. Q. I have a PC version but it appears to be only a binary. |
| 1663 | 2244 Where's the library? |
| 1529 | 2245 |
| 2246 A. You still need to copy the files from the distribution directory | |
|
1547
0efa240b1dbc
At the release of 1.0.1
Guido van Rossum <guido@python.org>
parents:
1541
diff
changeset
|
2247 "python/Lib" to your system. If you don't have the full distribution, |
|
2661
b4fd48e3a3b8
changed path references
Guido van Rossum <guido@python.org>
parents:
2660
diff
changeset
|
2248 you can get the file lib<version>.tar.gz from most ftp sites carrying |
|
b4fd48e3a3b8
changed path references
Guido van Rossum <guido@python.org>
parents:
2660
diff
changeset
|
2249 Python; this is a subset of the distribution containing just those |
|
2716
19b1195a3af8
next version; python.org changes
Guido van Rossum <guido@python.org>
parents:
2661
diff
changeset
|
2250 files, e.g. <URL:ftp://ftp.python.org/pub/python/src/lib1.1.tar.gz>. |
| 1529 | 2251 |
|
1579
021daabe69d8
Updated for existence of newsgroup and various misc things
Guido van Rossum <guido@python.org>
parents:
1547
diff
changeset
|
2252 Once you have installed the library, you need to point sys.path to it. |
|
021daabe69d8
Updated for existence of newsgroup and various misc things
Guido van Rossum <guido@python.org>
parents:
1547
diff
changeset
|
2253 Assuming the library is in C:\misc\python\lib, the following commands |
|
021daabe69d8
Updated for existence of newsgroup and various misc things
Guido van Rossum <guido@python.org>
parents:
1547
diff
changeset
|
2254 will point your Python interpreter to it (note the doubled backslashes |
|
021daabe69d8
Updated for existence of newsgroup and various misc things
Guido van Rossum <guido@python.org>
parents:
1547
diff
changeset
|
2255 -- you can also use single forward slashes instead): |
|
021daabe69d8
Updated for existence of newsgroup and various misc things
Guido van Rossum <guido@python.org>
parents:
1547
diff
changeset
|
2256 |
| 2048 | 2257 >>> import sys |
| 2258 >>> sys.path.insert(0, 'C:\\misc\\python\\lib') | |
| 2259 >>> | |
|
1579
021daabe69d8
Updated for existence of newsgroup and various misc things
Guido van Rossum <guido@python.org>
parents:
1547
diff
changeset
|
2260 |
|
021daabe69d8
Updated for existence of newsgroup and various misc things
Guido van Rossum <guido@python.org>
parents:
1547
diff
changeset
|
2261 For a more permanent effect, set the environment variable PYTHONPATH, |
|
021daabe69d8
Updated for existence of newsgroup and various misc things
Guido van Rossum <guido@python.org>
parents:
1547
diff
changeset
|
2262 as follows (talking to a DOS prompt): |
|
021daabe69d8
Updated for existence of newsgroup and various misc things
Guido van Rossum <guido@python.org>
parents:
1547
diff
changeset
|
2263 |
| 2048 | 2264 C> SET PYTHONPATH=C:\misc\python\lib |
|
1579
021daabe69d8
Updated for existence of newsgroup and various misc things
Guido van Rossum <guido@python.org>
parents:
1547
diff
changeset
|
2265 |
|
4278
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
2266 7.9. Q. Where's the documentation for the Mac or PC version? |
| 1529 | 2267 |
|
2661
b4fd48e3a3b8
changed path references
Guido van Rossum <guido@python.org>
parents:
2660
diff
changeset
|
2268 A. The documentation for the Unix version also applies to the Mac and |
|
b4fd48e3a3b8
changed path references
Guido van Rossum <guido@python.org>
parents:
2660
diff
changeset
|
2269 PC versions. Where applicable, differences are indicated in the text. |
| 1529 | 2270 |
|
4278
f6e824b27032
Rewrite sections on GUI and DOS/Windows, various other small edits,
Guido van Rossum <guido@python.org>
parents:
4250
diff
changeset
|
2271 7.10. Q. The Mac (PC) version doesn't seem to have any facilities for |
|
1547
0efa240b1dbc
At the release of 1.0.1
Guido van Rossum <guido@python.org>
parents:
1541
diff
changeset
|
2272 creating or editing programs apart from entering it interactively, and |
|
0efa240b1dbc
At the release of 1.0.1
Guido van Rossum <guido@python.org>
parents:
1541
diff
changeset
|
2273 there seems to be no way to save code that was entered interactively. |
|
0efa240b1dbc
At the release of 1.0.1
Guido van Rossum <guido@python.org>
parents:
1541
diff
changeset
|
2274 How do I create a Python program on the Mac (PC)? |
| 1529 | 2275 |
|
1903
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
2276 A. Use an external editor. On the Mac, BBEdit seems to be a popular |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
2277 no-frills text editor. I work like this: start the interpreter; edit |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
2278 a module file using BBedit; import and test it in the interpreter; |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
2279 edit again in BBedit; then use the built-in function reload() to |
|
e450bd43631a
New version: 1.14 (previous oine was misnumbered 1.12).
Guido van Rossum <guido@python.org>
parents:
1902
diff
changeset
|
2280 re-read the imported module; etc. |
|
1579
021daabe69d8
Updated for existence of newsgroup and various misc things
Guido van Rossum <guido@python.org>
parents:
1547
diff
changeset
|
2281 |
|
021daabe69d8
Updated for existence of newsgroup and various misc things
Guido van Rossum <guido@python.org>
parents:
1547
diff
changeset
|
2282 Regarding the same question for the PC, Kurt Wm. Hemr writes: "While |
|
021daabe69d8
Updated for existence of newsgroup and various misc things
Guido van Rossum <guido@python.org>
parents:
1547
diff
changeset
|
2283 anyone with a pulse could certainly figure out how to do the same on |
|
021daabe69d8
Updated for existence of newsgroup and various misc things
Guido van Rossum <guido@python.org>
parents:
1547
diff
changeset
|
2284 MS-Windows, I would recommend the NotGNU Emacs clone for MS-Windows. |
|
021daabe69d8
Updated for existence of newsgroup and various misc things
Guido van Rossum <guido@python.org>
parents:
1547
diff
changeset
|
2285 Not only can you easily resave and "reload()" from Python after making |
|
021daabe69d8
Updated for existence of newsgroup and various misc things
Guido van Rossum <guido@python.org>
parents:
1547
diff
changeset
|
2286 changes, but since WinNot auto-copies to the clipboard any text you |
|
021daabe69d8
Updated for existence of newsgroup and various misc things
Guido van Rossum <guido@python.org>
parents:
1547
diff
changeset
|
2287 select, you can simply select the entire procedure (function) which |
|
021daabe69d8
Updated for existence of newsgroup and various misc things
Guido van Rossum <guido@python.org>
parents:
1547
diff
changeset
|
2288 you changed in WinNot, switch to QWPython, and shift-ins to reenter |
|
021daabe69d8
Updated for existence of newsgroup and various misc things
Guido van Rossum <guido@python.org>
parents:
1547
diff
changeset
|
2289 the changed program unit." |