Mercurial > cpython-lru_cache-weakref

annotate Lib/contextlib.py @ 56748:8eff759d080f

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
Merged revisions 75711 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r75711 | mark.dickinson | 2009-10-26 11:59:30 +0000 (Mon, 26 Oct 2009) | 1 line Skip readline tests if readline module is not available. ........
author Mark Dickinson <dickinsm@gmail.com>
date Mon, 26 Oct 2009 12:01:06 +0000
parents e80859461de8
children 30e1d8d08105
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
55020
e80859461de8 remove nested from __all__
Benjamin Peterson <benjamin@python.org>
parents: 55018
diff changeset
7 __all__ = ["contextmanager", "closing"]
36737
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
8
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
9 class GeneratorContextManager(object):
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
10 """Helper for @contextmanager decorator."""
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
11
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
12 def __init__(self, gen):
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
13 self.gen = gen
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
14
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
15 def __enter__(self):
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
16 try:
41501
0c5019afc55b PEP 3114: rename .next() to .__next__() and add next() builtin.
Georg Brandl <georg@python.org>
parents: 40587
diff changeset
17 return next(self.gen)
36737
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
18 except StopIteration:
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
19 raise RuntimeError("generator didn't yield")
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
20
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
21 def __exit__(self, type, value, traceback):
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
22 if type is None:
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
23 try:
41501
0c5019afc55b PEP 3114: rename .next() to .__next__() and add next() builtin.
Georg Brandl <georg@python.org>
parents: 40587
diff changeset
24 next(self.gen)
36737
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
25 except StopIteration:
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
26 return
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
27 else:
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
28 raise RuntimeError("generator didn't stop")
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
29 else:
43756
317ba53cd45c Merged revisions 58742-58816 via svnmerge from
Guido van Rossum <guido@python.org>
parents: 43189
diff changeset
30 if value is None:
317ba53cd45c Merged revisions 58742-58816 via svnmerge from
Guido van Rossum <guido@python.org>
parents: 43189
diff changeset
31 # 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
32 # 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
33 value = type()
36737
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
34 try:
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
35 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
36 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
37 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
38 # 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
39 # 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
40 # 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
41 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
42 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
43 # 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
44 # 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
45 # 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
46 # 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
47 # 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
48 # 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
49 #
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 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
51 raise
36737
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
52
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
53
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
54 def contextmanager(func):
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
55 """@contextmanager decorator.
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
56
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
57 Typical usage:
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
58
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
59 @contextmanager
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
60 def some_generator(<arguments>):
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
61 <setup>
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
62 try:
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
63 yield <value>
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
64 finally:
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
65 <cleanup>
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
66
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
67 This makes this:
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
68
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
69 with some_generator(<arguments>) as <variable>:
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
70 <body>
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
71
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
72 equivalent to this:
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
73
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
74 <setup>
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
75 try:
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
76 <variable> = <value>
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
77 <body>
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
78 finally:
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
79 <cleanup>
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
80
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
81 """
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
82 @wraps(func)
36737
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
83 def helper(*args, **kwds):
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
84 return GeneratorContextManager(func(*args, **kwds))
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
85 return helper
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
86
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
87
38453
29ae5e0fc348 Much-needed merge (using svnmerge.py this time) of trunk changes into p3yk.
Thomas Wouters <thomas@python.org>
parents: 37879
diff changeset
88 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
89 """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
90
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
91 Code like this:
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
92
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
93 with closing(<module>.open(<arguments>)) as f:
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
94 <block>
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
95
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
96 is equivalent to this:
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 f = <module>.open(<arguments>)
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
99 try:
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
100 <block>
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
101 finally:
fa92fe15251a Updates to the with-statement:
Guido van Rossum <guido@python.org>
parents:
diff changeset
102 f.close()
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 """
38453
29ae5e0fc348 Much-needed merge (using svnmerge.py this time) of trunk changes into p3yk.
Thomas Wouters <thomas@python.org>
parents: 37879
diff changeset
105 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
106 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
107 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
108 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
109 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
110 self.thing.close()