Mercurial > cpython-lru_cache-weakref

annotate Lib/contextlib.py @ 69778:07613ea46dbc

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
Merge: I was right, hardconding the localhost IP doesn't work in linux-vserver.
author R David Murray <rdmurray@bitdance.com>
date Mon, 02 May 2011 08:48:00 -0400
parents c03f64c71b05
children e4ba097123f6
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
rev   line source
36737
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
1 """Utilities for with-statement contexts. See PEP 343."""
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
2
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
3 import sys
46664
031dfe455585 Merged revisions 62425-62429,62434-62436,62441,62444,62446-62448,62450-62455,62463,62465-62466,62469,62474,62476-62478,62480,62485,62492,62497-62498,62500,62507,62513-62514,62516,62521,62531,62535,62545-62546,62548-62551,62553-62559,62569,62574,62577,62593,62595,62604-62606,62608,62616,62626-62627,62636,62638,62644-62645,62647-62648,62651-62653,62656,62661,62663,62680,62686-62687,62696,62699-62703,62711 via svnmerge from
Christian Heimes <christian@cheimes.de>
parents: 43756
diff changeset
4 from functools import wraps
54404
3eb522dc3337 Deprecate contextlib.nested(). The with-statement now provides this functionality directly.
Raymond Hettinger <python@rcn.com>
parents: 46664
diff changeset
5 from warnings import warn
36737
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
6
62652
30e1d8d08105 Issue 9110. Adding ContextDecorator to contextlib. This enables the creation of APIs that act as decorators as well as context managers. contextlib.contextmanager changed to use ContextDecorator.
Michael Foord <fuzzyman@voidspace.org.uk>
parents: 55020
diff changeset
7 __all__ = ["contextmanager", "closing", "ContextDecorator"]
30e1d8d08105 Issue 9110. Adding ContextDecorator to contextlib. This enables the creation of APIs that act as decorators as well as context managers. contextlib.contextmanager changed to use ContextDecorator.
Michael Foord <fuzzyman@voidspace.org.uk>
parents: 55020
diff changeset
8
36737
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
9
62652
30e1d8d08105 Issue 9110. Adding ContextDecorator to contextlib. This enables the creation of APIs that act as decorators as well as context managers. contextlib.contextmanager changed to use ContextDecorator.
Michael Foord <fuzzyman@voidspace.org.uk>
parents: 55020
diff changeset
10 class ContextDecorator(object):
30e1d8d08105 Issue 9110. Adding ContextDecorator to contextlib. This enables the creation of APIs that act as decorators as well as context managers. contextlib.contextmanager changed to use ContextDecorator.
Michael Foord <fuzzyman@voidspace.org.uk>
parents: 55020
diff changeset
11 "A base class or mixin that enables context managers to work as decorators."
30e1d8d08105 Issue 9110. Adding ContextDecorator to contextlib. This enables the creation of APIs that act as decorators as well as context managers. contextlib.contextmanager changed to use ContextDecorator.
Michael Foord <fuzzyman@voidspace.org.uk>
parents: 55020
diff changeset
12 def __call__(self, func):
30e1d8d08105 Issue 9110. Adding ContextDecorator to contextlib. This enables the creation of APIs that act as decorators as well as context managers. contextlib.contextmanager changed to use ContextDecorator.
Michael Foord <fuzzyman@voidspace.org.uk>
parents: 55020
diff changeset
13 @wraps(func)
30e1d8d08105 Issue 9110. Adding ContextDecorator to contextlib. This enables the creation of APIs that act as decorators as well as context managers. contextlib.contextmanager changed to use ContextDecorator.
Michael Foord <fuzzyman@voidspace.org.uk>
parents: 55020
diff changeset
14 def inner(*args, **kwds):
30e1d8d08105 Issue 9110. Adding ContextDecorator to contextlib. This enables the creation of APIs that act as decorators as well as context managers. contextlib.contextmanager changed to use ContextDecorator.
Michael Foord <fuzzyman@voidspace.org.uk>
parents: 55020
diff changeset
15 with self:
30e1d8d08105 Issue 9110. Adding ContextDecorator to contextlib. This enables the creation of APIs that act as decorators as well as context managers. contextlib.contextmanager changed to use ContextDecorator.
Michael Foord <fuzzyman@voidspace.org.uk>
parents: 55020
diff changeset
16 return func(*args, **kwds)
30e1d8d08105 Issue 9110. Adding ContextDecorator to contextlib. This enables the creation of APIs that act as decorators as well as context managers. contextlib.contextmanager changed to use ContextDecorator.
Michael Foord <fuzzyman@voidspace.org.uk>
parents: 55020
diff changeset
17 return inner
30e1d8d08105 Issue 9110. Adding ContextDecorator to contextlib. This enables the creation of APIs that act as decorators as well as context managers. contextlib.contextmanager changed to use ContextDecorator.
Michael Foord <fuzzyman@voidspace.org.uk>
parents: 55020
diff changeset
18
30e1d8d08105 Issue 9110. Adding ContextDecorator to contextlib. This enables the creation of APIs that act as decorators as well as context managers. contextlib.contextmanager changed to use ContextDecorator.
Michael Foord <fuzzyman@voidspace.org.uk>
parents: 55020
diff changeset
19
67463
c03f64c71b05 Issue #10859: Make `contextlib.GeneratorContextManager` officially
Antoine Pitrou <solipsis@pitrou.net>
parents: 62652
diff changeset
20 class _GeneratorContextManager(ContextDecorator):
36737
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
21 """Helper for @contextmanager decorator."""
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
22
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
23 def __init__(self, gen):
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
24 self.gen = gen
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
25
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
26 def __enter__(self):
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
27 try:
41501
0c5019afc55b PEP 3114: rename .next() to .__next__() and add next() builtin.
Georg Brandl <georg@python.org>
parents: 40587
diff changeset
28 return next(self.gen)
36737
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
29 except StopIteration:
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
30 raise RuntimeError("generator didn't yield")
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
31
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
32 def __exit__(self, type, value, traceback):
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
33 if type is None:
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
34 try:
41501
0c5019afc55b PEP 3114: rename .next() to .__next__() and add next() builtin.
Georg Brandl <georg@python.org>
parents: 40587
diff changeset
35 next(self.gen)
36737
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
36 except StopIteration:
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
37 return
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
38 else:
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
39 raise RuntimeError("generator didn't stop")
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
40 else:
43756
317ba53cd45c Merged revisions 58742-58816 via svnmerge from
Guido van Rossum <guido@python.org>
parents: 43189
diff changeset
41 if value is None:
317ba53cd45c Merged revisions 58742-58816 via svnmerge from
Guido van Rossum <guido@python.org>
parents: 43189
diff changeset
42 # Need to force instantiation so we can reliably
317ba53cd45c Merged revisions 58742-58816 via svnmerge from
Guido van Rossum <guido@python.org>
parents: 43189
diff changeset
43 # tell if we get the same exception back
317ba53cd45c Merged revisions 58742-58816 via svnmerge from
Guido van Rossum <guido@python.org>
parents: 43189
diff changeset
44 value = type()
36737
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
45 try:
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
46 self.gen.throw(type, value, traceback)
37879
f731859e9b3b Merge p3yk branch with the trunk up to revision 45595. This breaks a fair
Thomas Wouters <thomas@python.org>
parents: 36926
diff changeset
47 raise RuntimeError("generator didn't stop after throw()")
40587
6b18a095c2e7 SF patch 1631942 by Collin Winter:
Guido van Rossum <guido@python.org>
parents: 38453
diff changeset
48 except StopIteration as exc:
37879
f731859e9b3b Merge p3yk branch with the trunk up to revision 45595. This breaks a fair
Thomas Wouters <thomas@python.org>
parents: 36926
diff changeset
49 # Suppress the exception *unless* it's the same exception that
f731859e9b3b Merge p3yk branch with the trunk up to revision 45595. This breaks a fair
Thomas Wouters <thomas@python.org>
parents: 36926
diff changeset
50 # was passed to throw(). This prevents a StopIteration
f731859e9b3b Merge p3yk branch with the trunk up to revision 45595. This breaks a fair
Thomas Wouters <thomas@python.org>
parents: 36926
diff changeset
51 # raised inside the "with" statement from being suppressed
f731859e9b3b Merge p3yk branch with the trunk up to revision 45595. This breaks a fair
Thomas Wouters <thomas@python.org>
parents: 36926
diff changeset
52 return exc is not value
f731859e9b3b Merge p3yk branch with the trunk up to revision 45595. This breaks a fair
Thomas Wouters <thomas@python.org>
parents: 36926
diff changeset
53 except:
f731859e9b3b Merge p3yk branch with the trunk up to revision 45595. This breaks a fair
Thomas Wouters <thomas@python.org>
parents: 36926
diff changeset
54 # only re-raise if it's *not* the exception that was
f731859e9b3b Merge p3yk branch with the trunk up to revision 45595. This breaks a fair
Thomas Wouters <thomas@python.org>
parents: 36926
diff changeset
55 # passed to throw(), because __exit__() must not raise
f731859e9b3b Merge p3yk branch with the trunk up to revision 45595. This breaks a fair
Thomas Wouters <thomas@python.org>
parents: 36926
diff changeset
56 # an exception unless __exit__() itself failed. But throw()
f731859e9b3b Merge p3yk branch with the trunk up to revision 45595. This breaks a fair
Thomas Wouters <thomas@python.org>
parents: 36926
diff changeset
57 # has to raise the exception to signal propagation, so this
f731859e9b3b Merge p3yk branch with the trunk up to revision 45595. This breaks a fair
Thomas Wouters <thomas@python.org>
parents: 36926
diff changeset
58 # fixes the impedance mismatch between the throw() protocol
f731859e9b3b Merge p3yk branch with the trunk up to revision 45595. This breaks a fair
Thomas Wouters <thomas@python.org>
parents: 36926
diff changeset
59 # and the __exit__() protocol.
f731859e9b3b Merge p3yk branch with the trunk up to revision 45595. This breaks a fair
Thomas Wouters <thomas@python.org>
parents: 36926
diff changeset
60 #
f731859e9b3b Merge p3yk branch with the trunk up to revision 45595. This breaks a fair
Thomas Wouters <thomas@python.org>
parents: 36926
diff changeset
61 if sys.exc_info()[1] is not value:
f731859e9b3b Merge p3yk branch with the trunk up to revision 45595. This breaks a fair
Thomas Wouters <thomas@python.org>
parents: 36926
diff changeset
62 raise
36737
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
63
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
64
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
65 def contextmanager(func):
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
66 """@contextmanager decorator.
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
67
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
68 Typical usage:
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
69
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
70 @contextmanager
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
71 def some_generator(<arguments>):
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
72 <setup>
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
73 try:
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
74 yield <value>
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
75 finally:
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
76 <cleanup>
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
77
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
78 This makes this:
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
79
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
80 with some_generator(<arguments>) as <variable>:
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
81 <body>
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
82
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
83 equivalent to this:
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
84
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
85 <setup>
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
86 try:
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
87 <variable> = <value>
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
88 <body>
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
89 finally:
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
90 <cleanup>
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
91
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
92 """
46664
031dfe455585 Merged revisions 62425-62429,62434-62436,62441,62444,62446-62448,62450-62455,62463,62465-62466,62469,62474,62476-62478,62480,62485,62492,62497-62498,62500,62507,62513-62514,62516,62521,62531,62535,62545-62546,62548-62551,62553-62559,62569,62574,62577,62593,62595,62604-62606,62608,62616,62626-62627,62636,62638,62644-62645,62647-62648,62651-62653,62656,62661,62663,62680,62686-62687,62696,62699-62703,62711 via svnmerge from
Christian Heimes <christian@cheimes.de>
parents: 43756
diff changeset
93 @wraps(func)
36737
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
94 def helper(*args, **kwds):
67463
c03f64c71b05 Issue #10859: Make `contextlib.GeneratorContextManager` officially
Antoine Pitrou <solipsis@pitrou.net>
parents: 62652
diff changeset
95 return _GeneratorContextManager(func(*args, **kwds))
36737
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
96 return helper
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
97
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
98
38453
29ae5e0fc348 Much-needed merge (using svnmerge.py this time) of trunk changes into p3yk.
Thomas Wouters <thomas@python.org>
parents: 37879
diff changeset
99 class closing(object):
29ae5e0fc348 Much-needed merge (using svnmerge.py this time) of trunk changes into p3yk.
Thomas Wouters <thomas@python.org>
parents: 37879
diff changeset
100 """Context to automatically close something at the end of a block.
36737
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
101
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
102 Code like this:
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
103
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
104 with closing(<module>.open(<arguments>)) as f:
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
105 <block>
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
106
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
107 is equivalent to this:
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
108
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
109 f = <module>.open(<arguments>)
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
110 try:
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
111 <block>
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
112 finally:
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
113 f.close()
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
114
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
115 """
38453
29ae5e0fc348 Much-needed merge (using svnmerge.py this time) of trunk changes into p3yk.
Thomas Wouters <thomas@python.org>
parents: 37879
diff changeset
116 def __init__(self, thing):
29ae5e0fc348 Much-needed merge (using svnmerge.py this time) of trunk changes into p3yk.
Thomas Wouters <thomas@python.org>
parents: 37879
diff changeset
117 self.thing = thing
29ae5e0fc348 Much-needed merge (using svnmerge.py this time) of trunk changes into p3yk.
Thomas Wouters <thomas@python.org>
parents: 37879
diff changeset
118 def __enter__(self):
29ae5e0fc348 Much-needed merge (using svnmerge.py this time) of trunk changes into p3yk.
Thomas Wouters <thomas@python.org>
parents: 37879
diff changeset
119 return self.thing
29ae5e0fc348 Much-needed merge (using svnmerge.py this time) of trunk changes into p3yk.
Thomas Wouters <thomas@python.org>
parents: 37879
diff changeset
120 def __exit__(self, *exc_info):
29ae5e0fc348 Much-needed merge (using svnmerge.py this time) of trunk changes into p3yk.
Thomas Wouters <thomas@python.org>
parents: 37879
diff changeset
121 self.thing.close()