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mirror of https://github.com/python/cpython.git synced 2024-11-30 10:41:14 +01:00
cpython/Lib/contextlib.py
Guido van Rossum 04110fb859 Merged revisions 57221-57391 via svnmerge from
svn+ssh://pythondev@svn.python.org/python/trunk

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  r57227 | facundo.batista | 2007-08-20 17:16:21 -0700 (Mon, 20 Aug 2007) | 5 lines


  Catch ProtocolError exceptions and include the header information in
  test output (to make it easier to debug test failures caused by
  problems in the server). [GSoC - Alan McIntyre]
........
  r57229 | mark.hammond | 2007-08-20 18:04:47 -0700 (Mon, 20 Aug 2007) | 5 lines

  [ 1761786 ] distutils.util.get_platform() return value on 64bit Windows
  As discussed on distutils-sig: Allows the generated installer name on
  64bit Windows platforms to be different than the name generated for
  32bit Windows platforms.
........
  r57230 | mark.hammond | 2007-08-20 18:05:16 -0700 (Mon, 20 Aug 2007) | 5 lines

  [ 1761786 ] distutils.util.get_platform() return value on 64bit Windows
  As discussed on distutils-sig: Allows the generated installer name on
  64bit Windows platforms to be different than the name generated for
  32bit Windows platforms.
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  r57253 | georg.brandl | 2007-08-20 23:01:18 -0700 (Mon, 20 Aug 2007) | 2 lines

  Demand version 2.5.1 since 2.5 has a bug with codecs.open context managers.
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  r57254 | georg.brandl | 2007-08-20 23:03:43 -0700 (Mon, 20 Aug 2007) | 2 lines

  Revert accidental checkins from last commit.
........
  r57255 | georg.brandl | 2007-08-20 23:07:08 -0700 (Mon, 20 Aug 2007) | 2 lines

  Bug #1777160: mention explicitly that e.g. -1**2 is -1.
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  r57256 | georg.brandl | 2007-08-20 23:12:19 -0700 (Mon, 20 Aug 2007) | 3 lines

  Bug #1777168: replace operator names "opa"... with "op1"... and mark everything up as literal,
  to enhance readability.
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  r57259 | facundo.batista | 2007-08-21 09:57:18 -0700 (Tue, 21 Aug 2007) | 8 lines


  Added test for behavior of operations on an unconnected SMTP object,
  and tests for NOOP, RSET, and VRFY. Corrected typo in a comment for
  testNonnumericPort. Added a check for constructing SMTP objects when
  non-numeric ports are included in the host name. Derived a server from
  SMTPServer to test various ESMTP/SMTP capabilities. Check that a
  second HELO to DebuggingServer returns an error. [GSoC - Alan McIntyre]
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  r57279 | skip.montanaro | 2007-08-22 12:02:16 -0700 (Wed, 22 Aug 2007) | 2 lines

  Note that BeOS is unsupported as of Python 2.6.
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  r57280 | skip.montanaro | 2007-08-22 12:05:21 -0700 (Wed, 22 Aug 2007) | 1 line

  whoops - need to check in configure as well
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  r57284 | alex.martelli | 2007-08-22 14:14:17 -0700 (Wed, 22 Aug 2007) | 5 lines

  Fix compile.c so that it records 0.0 and -0.0 as separate constants in a code
  object's co_consts tuple; add a test to show that the previous behavior (where
  these two constants were "collapsed" into one) causes serious malfunctioning.
........
  r57286 | gregory.p.smith | 2007-08-22 14:32:34 -0700 (Wed, 22 Aug 2007) | 3 lines

  stop leaving log.0000001 __db.00* and xxx.db turds in developer
  sandboxes when bsddb3 tests are run.
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  r57301 | jeffrey.yasskin | 2007-08-22 16:14:27 -0700 (Wed, 22 Aug 2007) | 3 lines

  When setup.py fails to find the necessary bits to build some modules, have it
  print a slightly more informative message.
........
  r57320 | brett.cannon | 2007-08-23 07:53:17 -0700 (Thu, 23 Aug 2007) | 2 lines

  Make test_runpy re-entrant.
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  r57324 | georg.brandl | 2007-08-23 10:54:11 -0700 (Thu, 23 Aug 2007) | 2 lines

  Bug #1768121: fix wrong/missing opcode docs.
........
  r57326 | georg.brandl | 2007-08-23 10:57:05 -0700 (Thu, 23 Aug 2007) | 2 lines

  Bug #1766421: "return code" vs. "status code".
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  r57328 | georg.brandl | 2007-08-23 11:08:06 -0700 (Thu, 23 Aug 2007) | 2 lines

  Second half of #1752175: #ifdef out references to PyImport_DynLoadFiletab if HAVE_DYNAMIC_LOADING is not defined.
........
  r57331 | georg.brandl | 2007-08-23 11:11:33 -0700 (Thu, 23 Aug 2007) | 2 lines

  Use try-except-finally in contextlib.
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  r57343 | georg.brandl | 2007-08-23 13:35:00 -0700 (Thu, 23 Aug 2007) | 2 lines

  Bug #1697820: document that the old slice protocol is still used by builtin types.
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  r57345 | georg.brandl | 2007-08-23 13:40:01 -0700 (Thu, 23 Aug 2007) | 2 lines

  Bug #1573854: fix docs for sqlite3 cursor rowcount attr.
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  r57347 | georg.brandl | 2007-08-23 13:50:23 -0700 (Thu, 23 Aug 2007) | 2 lines

  Bug #1694833: fix imp.find_module() docs wrt. packages.
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  r57348 | georg.brandl | 2007-08-23 13:53:28 -0700 (Thu, 23 Aug 2007) | 2 lines

  Bug #1594966: fix misleading usage example
........
  r57349 | georg.brandl | 2007-08-23 13:55:44 -0700 (Thu, 23 Aug 2007) | 2 lines

  Clarify wording a bit.
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  r57351 | georg.brandl | 2007-08-23 14:18:44 -0700 (Thu, 23 Aug 2007) | 2 lines

  Bug #1752332: httplib no longer uses socket.getaddrinfo().
........
  r57352 | georg.brandl | 2007-08-23 14:21:36 -0700 (Thu, 23 Aug 2007) | 2 lines

  Bug #1734111: document struct.Struct.size.
........
  r57353 | georg.brandl | 2007-08-23 14:27:57 -0700 (Thu, 23 Aug 2007) | 2 lines

  Bug #1688564: document os.path.join's absolute path behavior in the docstring.
........
  r57354 | georg.brandl | 2007-08-23 14:36:05 -0700 (Thu, 23 Aug 2007) | 2 lines

  Bug #1625381: clarify match vs search introduction.
........
  r57355 | georg.brandl | 2007-08-23 14:42:54 -0700 (Thu, 23 Aug 2007) | 2 lines

  Bug #1758696: more info about descriptors.
........
  r57357 | georg.brandl | 2007-08-23 14:55:57 -0700 (Thu, 23 Aug 2007) | 2 lines

  Patch #1779550: remove redundant code in logging.
........
  r57378 | gregory.p.smith | 2007-08-23 22:11:38 -0700 (Thu, 23 Aug 2007) | 2 lines

  Fix bug 1725856.
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  r57382 | georg.brandl | 2007-08-23 23:10:01 -0700 (Thu, 23 Aug 2007) | 2 lines

  uuid creation is now threadsafe, backport from py3k rev. 57375.
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  r57389 | georg.brandl | 2007-08-24 04:47:37 -0700 (Fri, 24 Aug 2007) | 2 lines

  Bug #1765375: fix stripping of unwanted LDFLAGS.
........
  r57391 | guido.van.rossum | 2007-08-24 07:53:14 -0700 (Fri, 24 Aug 2007) | 2 lines

  Fix silly typo in test name.
........
2007-08-24 16:32:05 +00:00

154 lines
4.0 KiB
Python

"""Utilities for with-statement contexts. See PEP 343."""
import sys
__all__ = ["contextmanager", "nested", "closing"]
class GeneratorContextManager(object):
"""Helper for @contextmanager decorator."""
def __init__(self, gen):
self.gen = gen
def __enter__(self):
try:
return next(self.gen)
except StopIteration:
raise RuntimeError("generator didn't yield")
def __exit__(self, type, value, traceback):
if type is None:
try:
next(self.gen)
except StopIteration:
return
else:
raise RuntimeError("generator didn't stop")
else:
try:
self.gen.throw(type, value, traceback)
raise RuntimeError("generator didn't stop after throw()")
except StopIteration as exc:
# Suppress the exception *unless* it's the same exception that
# was passed to throw(). This prevents a StopIteration
# raised inside the "with" statement from being suppressed
return exc is not value
except:
# only re-raise if it's *not* the exception that was
# passed to throw(), because __exit__() must not raise
# an exception unless __exit__() itself failed. But throw()
# has to raise the exception to signal propagation, so this
# fixes the impedance mismatch between the throw() protocol
# and the __exit__() protocol.
#
if sys.exc_info()[1] is not value:
raise
def contextmanager(func):
"""@contextmanager decorator.
Typical usage:
@contextmanager
def some_generator(<arguments>):
<setup>
try:
yield <value>
finally:
<cleanup>
This makes this:
with some_generator(<arguments>) as <variable>:
<body>
equivalent to this:
<setup>
try:
<variable> = <value>
<body>
finally:
<cleanup>
"""
def helper(*args, **kwds):
return GeneratorContextManager(func(*args, **kwds))
try:
helper.__name__ = func.__name__
helper.__doc__ = func.__doc__
helper.__dict__ = func.__dict__
except:
pass
return helper
@contextmanager
def nested(*managers):
"""Support multiple context managers in a single with-statement.
Code like this:
with nested(A, B, C) as (X, Y, Z):
<body>
is equivalent to this:
with A as X:
with B as Y:
with C as Z:
<body>
"""
exits = []
vars = []
exc = (None, None, None)
try:
for mgr in managers:
exit = mgr.__exit__
enter = mgr.__enter__
vars.append(enter())
exits.append(exit)
yield vars
except:
exc = sys.exc_info()
finally:
while exits:
exit = exits.pop()
try:
if exit(*exc):
exc = (None, None, None)
except:
exc = sys.exc_info()
if exc != (None, None, None):
# Don't rely on sys.exc_info() still containing
# the right information. Another exception may
# have been raised and caught by an exit method
raise exc[0], exc[1], exc[2]
class closing(object):
"""Context to automatically close something at the end of a block.
Code like this:
with closing(<module>.open(<arguments>)) as f:
<block>
is equivalent to this:
f = <module>.open(<arguments>)
try:
<block>
finally:
f.close()
"""
def __init__(self, thing):
self.thing = thing
def __enter__(self):
return self.thing
def __exit__(self, *exc_info):
self.thing.close()