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Nick Coghlan 2011-12-13 22:41:17 +10:00
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syntax: glob
*.swp
*.kate-swp
*.o
*.pyc
*.pyo
*.pyd
*.cover
*~
__pycache__
.coverage
coverage/
htmlcov/
_build/
dist/
MANIFEST

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A. HISTORY OF THE SOFTWARE
==========================
contextlib2 is a derivative of the contextlib module distributed by the PSF
as part of the Python standard library. According, it is itself redistributed
under the PSF license (reproduced in full below). As the contextlib module
was added only in Python 2.5, the licenses for earlier Python versions are
not applicable and have not been included.
Python was created in the early 1990s by Guido van Rossum at Stichting
Mathematisch Centrum (CWI, see http://www.cwi.nl) in the Netherlands
as a successor of a language called ABC. Guido remains Python's
principal author, although it includes many contributions from others.
In 1995, Guido continued his work on Python at the Corporation for
National Research Initiatives (CNRI, see http://www.cnri.reston.va.us)
in Reston, Virginia where he released several versions of the
software.
In May 2000, Guido and the Python core development team moved to
BeOpen.com to form the BeOpen PythonLabs team. In October of the same
year, the PythonLabs team moved to Digital Creations (now Zope
Corporation, see http://www.zope.com). In 2001, the Python Software
Foundation (PSF, see http://www.python.org/psf/) was formed, a
non-profit organization created specifically to own Python-related
Intellectual Property. Zope Corporation is a sponsoring member of
the PSF.
All Python releases are Open Source (see http://www.opensource.org for
the Open Source Definition). Historically, most, but not all, Python
releases have also been GPL-compatible; the table below summarizes
the various releases that included the contextlib module.
Release Derived Year Owner GPL-
from compatible? (1)
2.5 2.4 2006 PSF yes
2.5.1 2.5 2007 PSF yes
2.5.2 2.5.1 2008 PSF yes
2.5.3 2.5.2 2008 PSF yes
2.6 2.5 2008 PSF yes
2.6.1 2.6 2008 PSF yes
2.6.2 2.6.1 2009 PSF yes
2.6.3 2.6.2 2009 PSF yes
2.6.4 2.6.3 2009 PSF yes
2.6.5 2.6.4 2010 PSF yes
3.0 2.6 2008 PSF yes
3.0.1 3.0 2009 PSF yes
3.1 3.0.1 2009 PSF yes
3.1.1 3.1 2009 PSF yes
3.1.2 3.1.1 2010 PSF yes
3.1.3 3.1.2 2010 PSF yes
3.1.4 3.1.3 2011 PSF yes
3.2 3.1 2011 PSF yes
3.2.1 3.2 2011 PSF yes
3.2.2 3.2.1 2011 PSF yes
3.3 3.2 2012 PSF yes
Footnotes:
(1) GPL-compatible doesn't mean that we're distributing Python under
the GPL. All Python licenses, unlike the GPL, let you distribute
a modified version without making your changes open source. The
GPL-compatible licenses make it possible to combine Python with
other software that is released under the GPL; the others don't.
Thanks to the many outside volunteers who have worked under Guido's
direction to make these releases possible.
B. TERMS AND CONDITIONS FOR ACCESSING OR OTHERWISE USING PYTHON
===============================================================
PYTHON SOFTWARE FOUNDATION LICENSE VERSION 2
--------------------------------------------
1. This LICENSE AGREEMENT is between the Python Software Foundation
("PSF"), and the Individual or Organization ("Licensee") accessing and
otherwise using this software ("Python") in source or binary form and
its associated documentation.
2. Subject to the terms and conditions of this License Agreement, PSF hereby
grants Licensee a nonexclusive, royalty-free, world-wide license to reproduce,
analyze, test, perform and/or display publicly, prepare derivative works,
distribute, and otherwise use Python alone or in any derivative version,
provided, however, that PSF's License Agreement and PSF's notice of copyright,
i.e., "Copyright (c) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010,
2011 Python Software Foundation; All Rights Reserved" are retained in Python
alone or in any derivative version prepared by Licensee.
3. In the event Licensee prepares a derivative work that is based on
or incorporates Python or any part thereof, and wants to make
the derivative work available to others as provided herein, then
Licensee hereby agrees to include in any such work a brief summary of
the changes made to Python.
4. PSF is making Python available to Licensee on an "AS IS"
basis. PSF MAKES NO REPRESENTATIONS OR WARRANTIES, EXPRESS OR
IMPLIED. BY WAY OF EXAMPLE, BUT NOT LIMITATION, PSF MAKES NO AND
DISCLAIMS ANY REPRESENTATION OR WARRANTY OF MERCHANTABILITY OR FITNESS
FOR ANY PARTICULAR PURPOSE OR THAT THE USE OF PYTHON WILL NOT
INFRINGE ANY THIRD PARTY RIGHTS.
5. PSF SHALL NOT BE LIABLE TO LICENSEE OR ANY OTHER USERS OF PYTHON
FOR ANY INCIDENTAL, SPECIAL, OR CONSEQUENTIAL DAMAGES OR LOSS AS
A RESULT OF MODIFYING, DISTRIBUTING, OR OTHERWISE USING PYTHON,
OR ANY DERIVATIVE THEREOF, EVEN IF ADVISED OF THE POSSIBILITY THEREOF.
6. This License Agreement will automatically terminate upon a material
breach of its terms and conditions.
7. Nothing in this License Agreement shall be deemed to create any
relationship of agency, partnership, or joint venture between PSF and
Licensee. This License Agreement does not grant permission to use PSF
trademarks or trade name in a trademark sense to endorse or promote
products or services of Licensee, or any third party.
8. By copying, installing or otherwise using Python, Licensee
agrees to be bound by the terms and conditions of this License
Agreement.

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contextlib2 is a backport of the standard library's contextlib module to earlier Python versions.
It also serves as a real world proving ground for possible future enhancements to the standard library version.

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"""contextlib2 - backports and enhancements to the contextlib module"""
import sys
from collections import deque
from functools import wraps
__all__ = ["contextmanager", "closing", "ContextDecorator", "CleanupManager"]
class ContextDecorator(object):
"A base class or mixin that enables context managers to work as decorators."
def refresh_cm(self):
"""Returns the context manager used to actually wrap the call to the
decorated function.
The default implementation just returns *self*.
Overriding this method allows otherwise one-shot context managers
like _GeneratorContextManager to support use as decorators via
implicit recreation.
"""
return self
def __call__(self, func):
@wraps(func)
def inner(*args, **kwds):
with self.refresh_cm():
return func(*args, **kwds)
return inner
class _GeneratorContextManager(ContextDecorator):
"""Helper for @contextmanager decorator."""
def __init__(self, func, *args, **kwds):
self.gen = func(*args, **kwds)
self.func, self.args, self.kwds = func, args, kwds
def refresh_cm(self):
# _GCM instances are one-shot context managers, so the
# CM must be recreated each time a decorated function is
# called
return self.__class__(self.func, *self.args, **self.kwds)
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:
if value is None:
# Need to force instantiation so we can reliably
# tell if we get the same exception back
value = type()
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>
"""
@wraps(func)
def helper(*args, **kwds):
return _GeneratorContextManager(func, *args, **kwds)
return helper
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()
class CleanupManager(object):
"""Context for programmatic management of resource cleanup
For example:
with CleanupManager() as cmgr:
files = [cmgr.enter_context(fname) for fname in filenames]
# All opened files will automatically be closed at the end of
# the with statement, even if attempts to open files later
# in the list throw an exception
"""
def __init__(self):
self._callbacks = deque()
def register_exit(self, exit):
"""Accepts callbacks with the same signature as context manager __exit__ methods
Can also suppress exceptions the same way __exit__ methods can.
"""
self._callbacks.append(exit)
return exit # Allow use as a decorator
def register(self, _cb, *args, **kwds):
"""Accepts arbitrary callbacks and arguments. Cannot suppress exceptions."""
def _wrapper(exc_type, exc, tb):
_cb(*args, **kwds)
return self.register_exit(_wrapper)
def enter_context(self, cm):
"""Accepts and automatically enters other context managers"""
# We look up the special methods on the type to match the with statement
_cm_type = type(cm)
_exit = _cm_type.__exit__
result = _cm_type.__enter__(cm)
def _exit_wrapper(*exc_details):
return _exit(cm, *exc_details)
self.register_exit(_exit_wrapper)
return result
def close(self):
"""Immediately cleanup all registered resources"""
self.__exit__(None, None, None)
def __enter__(self):
return self
def __exit__(self, *exc_details):
if not self._callbacks:
return
# This looks complicated, but it is really just
# setting up a chain of try-expect statements to ensure
# that outer callbacks still get invoked even if an
# inner one throws an exception
def _invoke_next_callback(exc_details):
# Callbacks are removed from the list in FIFO order
# but the recursion means they're *invoked* in LIFO order
cb = self._callbacks.popleft()
if not self._callbacks:
# Innermost callback is invoked directly
return cb(*exc_details)
# More callbacks left, so descend another level in the stack
try:
suppress_exc = _invoke_next_callback(exc_details)
except:
suppress_exc = cb(*sys.exc_info())
# Check if this cb suppressed the inner exception
if not suppress_exc:
raise
else:
# Check if inner cb suppressed the original exception
if suppress_exc:
exc_details = (None, None, None)
suppress_exc = cb(*exc_details) or suppress_exc
return suppress_exc
# Kick off the recursive chain
return _invoke_next_callback(exc_details)

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# Makefile for Sphinx documentation
#
# You can set these variables from the command line.
SPHINXOPTS =
SPHINXBUILD = sphinx-build
PAPER =
BUILDDIR = _build
# Internal variables.
PAPEROPT_a4 = -D latex_paper_size=a4
PAPEROPT_letter = -D latex_paper_size=letter
ALLSPHINXOPTS = -d $(BUILDDIR)/doctrees $(PAPEROPT_$(PAPER)) $(SPHINXOPTS) .
.PHONY: help clean html dirhtml singlehtml pickle json htmlhelp qthelp devhelp epub latex latexpdf text man changes linkcheck doctest
help:
@echo "Please use \`make <target>' where <target> is one of"
@echo " html to make standalone HTML files"
@echo " dirhtml to make HTML files named index.html in directories"
@echo " singlehtml to make a single large HTML file"
@echo " pickle to make pickle files"
@echo " json to make JSON files"
@echo " htmlhelp to make HTML files and a HTML help project"
@echo " qthelp to make HTML files and a qthelp project"
@echo " devhelp to make HTML files and a Devhelp project"
@echo " epub to make an epub"
@echo " latex to make LaTeX files, you can set PAPER=a4 or PAPER=letter"
@echo " latexpdf to make LaTeX files and run them through pdflatex"
@echo " text to make text files"
@echo " man to make manual pages"
@echo " changes to make an overview of all changed/added/deprecated items"
@echo " linkcheck to check all external links for integrity"
@echo " doctest to run all doctests embedded in the documentation (if enabled)"
clean:
-rm -rf $(BUILDDIR)/*
html:
$(SPHINXBUILD) -b html $(ALLSPHINXOPTS) $(BUILDDIR)/html
@echo
@echo "Build finished. The HTML pages are in $(BUILDDIR)/html."
dirhtml:
$(SPHINXBUILD) -b dirhtml $(ALLSPHINXOPTS) $(BUILDDIR)/dirhtml
@echo
@echo "Build finished. The HTML pages are in $(BUILDDIR)/dirhtml."
singlehtml:
$(SPHINXBUILD) -b singlehtml $(ALLSPHINXOPTS) $(BUILDDIR)/singlehtml
@echo
@echo "Build finished. The HTML page is in $(BUILDDIR)/singlehtml."
pickle:
$(SPHINXBUILD) -b pickle $(ALLSPHINXOPTS) $(BUILDDIR)/pickle
@echo
@echo "Build finished; now you can process the pickle files."
json:
$(SPHINXBUILD) -b json $(ALLSPHINXOPTS) $(BUILDDIR)/json
@echo
@echo "Build finished; now you can process the JSON files."
htmlhelp:
$(SPHINXBUILD) -b htmlhelp $(ALLSPHINXOPTS) $(BUILDDIR)/htmlhelp
@echo
@echo "Build finished; now you can run HTML Help Workshop with the" \
".hhp project file in $(BUILDDIR)/htmlhelp."
qthelp:
$(SPHINXBUILD) -b qthelp $(ALLSPHINXOPTS) $(BUILDDIR)/qthelp
@echo
@echo "Build finished; now you can run "qcollectiongenerator" with the" \
".qhcp project file in $(BUILDDIR)/qthelp, like this:"
@echo "# qcollectiongenerator $(BUILDDIR)/qthelp/contextlib2.qhcp"
@echo "To view the help file:"
@echo "# assistant -collectionFile $(BUILDDIR)/qthelp/contextlib2.qhc"
devhelp:
$(SPHINXBUILD) -b devhelp $(ALLSPHINXOPTS) $(BUILDDIR)/devhelp
@echo
@echo "Build finished."
@echo "To view the help file:"
@echo "# mkdir -p $$HOME/.local/share/devhelp/contextlib2"
@echo "# ln -s $(BUILDDIR)/devhelp $$HOME/.local/share/devhelp/contextlib2"
@echo "# devhelp"
epub:
$(SPHINXBUILD) -b epub $(ALLSPHINXOPTS) $(BUILDDIR)/epub
@echo
@echo "Build finished. The epub file is in $(BUILDDIR)/epub."
latex:
$(SPHINXBUILD) -b latex $(ALLSPHINXOPTS) $(BUILDDIR)/latex
@echo
@echo "Build finished; the LaTeX files are in $(BUILDDIR)/latex."
@echo "Run \`make' in that directory to run these through (pdf)latex" \
"(use \`make latexpdf' here to do that automatically)."
latexpdf:
$(SPHINXBUILD) -b latex $(ALLSPHINXOPTS) $(BUILDDIR)/latex
@echo "Running LaTeX files through pdflatex..."
make -C $(BUILDDIR)/latex all-pdf
@echo "pdflatex finished; the PDF files are in $(BUILDDIR)/latex."
text:
$(SPHINXBUILD) -b text $(ALLSPHINXOPTS) $(BUILDDIR)/text
@echo
@echo "Build finished. The text files are in $(BUILDDIR)/text."
man:
$(SPHINXBUILD) -b man $(ALLSPHINXOPTS) $(BUILDDIR)/man
@echo
@echo "Build finished. The manual pages are in $(BUILDDIR)/man."
changes:
$(SPHINXBUILD) -b changes $(ALLSPHINXOPTS) $(BUILDDIR)/changes
@echo
@echo "The overview file is in $(BUILDDIR)/changes."
linkcheck:
$(SPHINXBUILD) -b linkcheck $(ALLSPHINXOPTS) $(BUILDDIR)/linkcheck
@echo
@echo "Link check complete; look for any errors in the above output " \
"or in $(BUILDDIR)/linkcheck/output.txt."
doctest:
$(SPHINXBUILD) -b doctest $(ALLSPHINXOPTS) $(BUILDDIR)/doctest
@echo "Testing of doctests in the sources finished, look at the " \
"results in $(BUILDDIR)/doctest/output.txt."

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# -*- coding: utf-8 -*-
#
# contextlib2 documentation build configuration file, created by
# sphinx-quickstart on Tue Dec 13 20:29:56 2011.
#
# This file is execfile()d with the current directory set to its containing dir.
#
# Note that not all possible configuration values are present in this
# autogenerated file.
#
# All configuration values have a default; values that are commented out
# serve to show the default.
import sys, os
# If extensions (or modules to document with autodoc) are in another directory,
# add these directories to sys.path here. If the directory is relative to the
# documentation root, use os.path.abspath to make it absolute, like shown here.
#sys.path.insert(0, os.path.abspath('.'))
# -- General configuration -----------------------------------------------------
# If your documentation needs a minimal Sphinx version, state it here.
#needs_sphinx = '1.0'
# Add any Sphinx extension module names here, as strings. They can be extensions
# coming with Sphinx (named 'sphinx.ext.*') or your custom ones.
extensions = ['sphinx.ext.intersphinx']
# Add any paths that contain templates here, relative to this directory.
templates_path = ['_templates']
# The suffix of source filenames.
source_suffix = '.rst'
# The encoding of source files.
#source_encoding = 'utf-8-sig'
# The master toctree document.
master_doc = 'index'
# General information about the project.
project = u'contextlib2'
copyright = u'2011, Nick Coghlan'
# The version info for the project you're documenting, acts as replacement for
# |version| and |release|, also used in various other places throughout the
# built documents.
#
# The short X.Y version.
version = '0.1'
# The full version, including alpha/beta/rc tags.
release = '0.1'
# The language for content autogenerated by Sphinx. Refer to documentation
# for a list of supported languages.
#language = None
# There are two options for replacing |today|: either, you set today to some
# non-false value, then it is used:
#today = ''
# Else, today_fmt is used as the format for a strftime call.
#today_fmt = '%B %d, %Y'
# List of patterns, relative to source directory, that match files and
# directories to ignore when looking for source files.
exclude_patterns = ['_build']
# The reST default role (used for this markup: `text`) to use for all documents.
#default_role = None
# If true, '()' will be appended to :func: etc. cross-reference text.
#add_function_parentheses = True
# If true, the current module name will be prepended to all description
# unit titles (such as .. function::).
add_module_names = False
# If true, sectionauthor and moduleauthor directives will be shown in the
# output. They are ignored by default.
#show_authors = False
# The name of the Pygments (syntax highlighting) style to use.
pygments_style = 'sphinx'
# A list of ignored prefixes for module index sorting.
#modindex_common_prefix = []
# -- Options for HTML output ---------------------------------------------------
# The theme to use for HTML and HTML Help pages. See the documentation for
# a list of builtin themes.
html_theme = 'default'
# Theme options are theme-specific and customize the look and feel of a theme
# further. For a list of options available for each theme, see the
# documentation.
#html_theme_options = {}
# Add any paths that contain custom themes here, relative to this directory.
#html_theme_path = []
# The name for this set of Sphinx documents. If None, it defaults to
# "<project> v<release> documentation".
#html_title = None
# A shorter title for the navigation bar. Default is the same as html_title.
#html_short_title = None
# The name of an image file (relative to this directory) to place at the top
# of the sidebar.
#html_logo = None
# The name of an image file (within the static path) to use as favicon of the
# docs. This file should be a Windows icon file (.ico) being 16x16 or 32x32
# pixels large.
#html_favicon = None
# Add any paths that contain custom static files (such as style sheets) here,
# relative to this directory. They are copied after the builtin static files,
# so a file named "default.css" will overwrite the builtin "default.css".
html_static_path = ['_static']
# If not '', a 'Last updated on:' timestamp is inserted at every page bottom,
# using the given strftime format.
#html_last_updated_fmt = '%b %d, %Y'
# If true, SmartyPants will be used to convert quotes and dashes to
# typographically correct entities.
#html_use_smartypants = True
# Custom sidebar templates, maps document names to template names.
#html_sidebars = {}
# Additional templates that should be rendered to pages, maps page names to
# template names.
#html_additional_pages = {}
# If false, no module index is generated.
#html_domain_indices = True
# If false, no index is generated.
#html_use_index = True
# If true, the index is split into individual pages for each letter.
#html_split_index = False
# If true, links to the reST sources are added to the pages.
#html_show_sourcelink = True
# If true, "Created using Sphinx" is shown in the HTML footer. Default is True.
#html_show_sphinx = True
# If true, "(C) Copyright ..." is shown in the HTML footer. Default is True.
#html_show_copyright = True
# If true, an OpenSearch description file will be output, and all pages will
# contain a <link> tag referring to it. The value of this option must be the
# base URL from which the finished HTML is served.
#html_use_opensearch = ''
# This is the file name suffix for HTML files (e.g. ".xhtml").
#html_file_suffix = None
# Output file base name for HTML help builder.
htmlhelp_basename = 'contextlib2doc'
# -- Options for LaTeX output --------------------------------------------------
# The paper size ('letter' or 'a4').
#latex_paper_size = 'letter'
# The font size ('10pt', '11pt' or '12pt').
#latex_font_size = '10pt'
# Grouping the document tree into LaTeX files. List of tuples
# (source start file, target name, title, author, documentclass [howto/manual]).
latex_documents = [
('index', 'contextlib2.tex', u'contextlib2 Documentation',
u'Nick Coghlan', 'manual'),
]
# The name of an image file (relative to this directory) to place at the top of
# the title page.
#latex_logo = None
# For "manual" documents, if this is true, then toplevel headings are parts,
# not chapters.
#latex_use_parts = False
# If true, show page references after internal links.
#latex_show_pagerefs = False
# If true, show URL addresses after external links.
#latex_show_urls = False
# Additional stuff for the LaTeX preamble.
#latex_preamble = ''
# Documents to append as an appendix to all manuals.
#latex_appendices = []
# If false, no module index is generated.
#latex_domain_indices = True
# -- Options for manual page output --------------------------------------------
# One entry per manual page. List of tuples
# (source start file, name, description, authors, manual section).
man_pages = [
('index', 'contextlib2', u'contextlib2 Documentation',
[u'Nick Coghlan'], 1)
]
# Example configuration for intersphinx: refer to the Python 3 standard library.
intersphinx_mapping = {'http://docs.python.org/py3k': None}

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.. contextlib2 documentation master file, created by
sphinx-quickstart on Tue Dec 13 20:29:56 2011.
You can adapt this file completely to your liking, but it should at least
contain the root `toctree` directive.
contextlib2 --- Updated utilities for with-statement contexts
=============================================================
.. module:: contextlib2
:synopsis: Backports and future enhancements for the contextlib module
This module provides backports of features in the latest version of the
standard library's :mod:`contextlib` module to earlier Python versions. It
also serves as a real world proving ground for potential future enhancements
to that module.
Like :mod:`contextlib`, this module provides utilities for common tasks
involving the ``with`` statement.
Additions Relative to the Standard Library
------------------------------------------
This module is primarily a backport of the Python 3.2 version of
:mod:`contextlib` to earlier releases. However, it is also a proving ground
for new features not yet part of the standard library. Those new features
are currently:
* :meth:`ContextDecorator.refresh_cm`
* :class:`CleanupManager`
API Reference
-------------
.. function:: @contextmanager
This function is a decorator that can be used to define a factory
function for ``with`` statement context managers, without needing to
create a class or separate :meth:`__enter__` and :meth:`__exit__` methods.
A simple example (this is not recommended as a real way of generating HTML!)::
from contextlib import contextmanager
@contextmanager
def tag(name):
print("<%s>" % name)
yield
print("</%s>" % name)
>>> with tag("h1"):
... print("foo")
...
<h1>
foo
</h1>
The function being decorated must return a generator-iterator when
called. This iterator must yield exactly one value, which will be bound to
the targets in the ``with`` statement's ``as`` clause, if any.
At the point where the generator yields, the block nested in the ``with``
statement is executed. The generator is then resumed after the block is exited.
If an unhandled exception occurs in the block, it is reraised inside the
generator at the point where the yield occurred. Thus, you can use a
``try``...\ ``except``...\ ``finally`` statement to trap
the error (if any), or ensure that some cleanup takes place. If an exception is
trapped merely in order to log it or to perform some action (rather than to
suppress it entirely), the generator must reraise that exception. Otherwise the
generator context manager will indicate to the ``with`` statement that
the exception has been handled, and execution will resume with the statement
immediately following the ``with`` statement.
:func:`contextmanager` uses :class:`ContextDecorator` so the context managers
it creates can be used as decorators as well as in ``with`` statements.
When used as a decorator, a new generator instance is implicitly created on
each function call (this allows the otherwise "one-shot" context managers
created by :func:`contextmanager` to meet the requirement that context
managers support multiple invocations in order to be used as decorators).
.. function:: closing(thing)
Return a context manager that closes *thing* upon completion of the block. This
is basically equivalent to::
from contextlib import contextmanager
@contextmanager
def closing(thing):
try:
yield thing
finally:
thing.close()
And lets you write code like this::
from contextlib import closing
from urllib.request import urlopen
with closing(urlopen('http://www.python.org')) as page:
for line in page:
print(line)
without needing to explicitly close ``page``. Even if an error occurs,
``page.close()`` will be called when the ``with`` block is exited.
.. class:: ContextDecorator()
A base class that enables a context manager to also be used as a decorator.
Context managers inheriting from ``ContextDecorator`` have to implement
:meth:`__enter__` and :meth:`__exit__` as normal. :meth:`__exit__` retains its optional
exception handling even when used as a decorator.
``ContextDecorator`` is used by :func:`contextmanager`, so you get this
functionality automatically.
Example of ``ContextDecorator``::
from contextlib import ContextDecorator
class mycontext(ContextDecorator):
def __enter__(self):
print('Starting')
return self
def __exit__(self, *exc):
print('Finishing')
return False
>>> @mycontext()
... def function():
... print('The bit in the middle')
...
>>> function()
Starting
The bit in the middle
Finishing
>>> with mycontext():
... print('The bit in the middle')
...
Starting
The bit in the middle
Finishing
This change is just syntactic sugar for any construct of the following form::
def f():
with cm():
# Do stuff
``ContextDecorator`` lets you instead write::
@cm()
def f():
# Do stuff
It makes it clear that the ``cm`` applies to the whole function, rather than
just a piece of it (and saving an indentation level is nice, too).
Existing context managers that already have a base class can be extended by
using ``ContextDecorator`` as a mixin class::
from contextlib import ContextDecorator
class mycontext(ContextBaseClass, ContextDecorator):
def __enter__(self):
return self
def __exit__(self, *exc):
return False
.. method:: refresh_cm()
This method is invoked each time a call is made to a decorated function.
The default implementation just returns *self*.
As the decorated function must be able to be called multiple times, the
underlying context manager must normally support use in multiple
``with`` statements (preferably in a thread-safe manner). If
this is not the case, then the context manager must define this method
and return a *new* copy of the context manager on each invocation.
This may involve keeping a copy of the original arguments used to
first initialise the context manager.
.. class:: CleanupManager()
A context manager that is designed to make it easy to programmatically
combine other context managers and cleanup functions, that are either
optional or driven by input data.
For example, a set of files may easily be handled in a single with
statement as follows::
with CleanupManager() as cmgr:
files = [cmgr.enter_context(fname) for fname in filenames]
# All opened files will automatically be closed at the end of
# the with statement, even if attempts to open files later
# in the list throw an exception
.. method:: register_exit(exit):
Accepts callbacks with the same signature as context manager
:meth:`__exit__` methods
By returing true values, these callbacks can suppress exceptions the
same way context manager :meth:`__exit__` methods can.
.. method:: register(_cb, *args, **kwds):
Accepts arbitrary callbacks and arguments. These callbacks cannot
suppress exceptions.
.. method:: enter_context(cm):
Accepts and automatically enters other context managers. These
context managers may suppress exceptions just as they normally would.
.. method:: close()
Immediately cleans up all registered resources, resetting the manager
to its initial state in the process.
Obtaining the Module
====================
This module can be installed directly from the `Python Package Index`_ with
pip_::
pip install contextlib2
Alternatively, you can download and unpack it manually from the `contextlib2
PyPI page`_.
There are no operating system or distribution specific versions of this
module - it is a pure Python module that should work on all platforms.
Supported Python versions are 2.7 and 3.2+.
.. _Python Package Index: http://pypi.python.org
.. _pip: http://www.pip-installer.org
.. _contextlib2 pypi page: http://pypi.python.org/pypi/contextlib2
Development and Support
-----------------------
WalkDir is developed and maintained on BitBucket_. Problems and suggested
improvements can be posted to the `issue tracker`_.
.. _BitBucket: https://bitbucket.org/ncoghlan/contextlib2/overview
.. _issue tracker: https://bitbucket.org/ncoghlan/contextlib2/issues?status=new&status=open
Indices and tables
==================
* :ref:`genindex`
* :ref:`search`

170
docs/make.bat Normal file
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@ECHO OFF
REM Command file for Sphinx documentation
if "%SPHINXBUILD%" == "" (
set SPHINXBUILD=sphinx-build
)
set BUILDDIR=_build
set ALLSPHINXOPTS=-d %BUILDDIR%/doctrees %SPHINXOPTS% .
if NOT "%PAPER%" == "" (
set ALLSPHINXOPTS=-D latex_paper_size=%PAPER% %ALLSPHINXOPTS%
)
if "%1" == "" goto help
if "%1" == "help" (
:help
echo.Please use `make ^<target^>` where ^<target^> is one of
echo. html to make standalone HTML files
echo. dirhtml to make HTML files named index.html in directories
echo. singlehtml to make a single large HTML file
echo. pickle to make pickle files
echo. json to make JSON files
echo. htmlhelp to make HTML files and a HTML help project
echo. qthelp to make HTML files and a qthelp project
echo. devhelp to make HTML files and a Devhelp project
echo. epub to make an epub
echo. latex to make LaTeX files, you can set PAPER=a4 or PAPER=letter
echo. text to make text files
echo. man to make manual pages
echo. changes to make an overview over all changed/added/deprecated items
echo. linkcheck to check all external links for integrity
echo. doctest to run all doctests embedded in the documentation if enabled
goto end
)
if "%1" == "clean" (
for /d %%i in (%BUILDDIR%\*) do rmdir /q /s %%i
del /q /s %BUILDDIR%\*
goto end
)
if "%1" == "html" (
%SPHINXBUILD% -b html %ALLSPHINXOPTS% %BUILDDIR%/html
if errorlevel 1 exit /b 1
echo.
echo.Build finished. The HTML pages are in %BUILDDIR%/html.
goto end
)
if "%1" == "dirhtml" (
%SPHINXBUILD% -b dirhtml %ALLSPHINXOPTS% %BUILDDIR%/dirhtml
if errorlevel 1 exit /b 1
echo.
echo.Build finished. The HTML pages are in %BUILDDIR%/dirhtml.
goto end
)
if "%1" == "singlehtml" (
%SPHINXBUILD% -b singlehtml %ALLSPHINXOPTS% %BUILDDIR%/singlehtml
if errorlevel 1 exit /b 1
echo.
echo.Build finished. The HTML pages are in %BUILDDIR%/singlehtml.
goto end
)
if "%1" == "pickle" (
%SPHINXBUILD% -b pickle %ALLSPHINXOPTS% %BUILDDIR%/pickle
if errorlevel 1 exit /b 1
echo.
echo.Build finished; now you can process the pickle files.
goto end
)
if "%1" == "json" (
%SPHINXBUILD% -b json %ALLSPHINXOPTS% %BUILDDIR%/json
if errorlevel 1 exit /b 1
echo.
echo.Build finished; now you can process the JSON files.
goto end
)
if "%1" == "htmlhelp" (
%SPHINXBUILD% -b htmlhelp %ALLSPHINXOPTS% %BUILDDIR%/htmlhelp
if errorlevel 1 exit /b 1
echo.
echo.Build finished; now you can run HTML Help Workshop with the ^
.hhp project file in %BUILDDIR%/htmlhelp.
goto end
)
if "%1" == "qthelp" (
%SPHINXBUILD% -b qthelp %ALLSPHINXOPTS% %BUILDDIR%/qthelp
if errorlevel 1 exit /b 1
echo.
echo.Build finished; now you can run "qcollectiongenerator" with the ^
.qhcp project file in %BUILDDIR%/qthelp, like this:
echo.^> qcollectiongenerator %BUILDDIR%\qthelp\contextlib2.qhcp
echo.To view the help file:
echo.^> assistant -collectionFile %BUILDDIR%\qthelp\contextlib2.ghc
goto end
)
if "%1" == "devhelp" (
%SPHINXBUILD% -b devhelp %ALLSPHINXOPTS% %BUILDDIR%/devhelp
if errorlevel 1 exit /b 1
echo.
echo.Build finished.
goto end
)
if "%1" == "epub" (
%SPHINXBUILD% -b epub %ALLSPHINXOPTS% %BUILDDIR%/epub
if errorlevel 1 exit /b 1
echo.
echo.Build finished. The epub file is in %BUILDDIR%/epub.
goto end
)
if "%1" == "latex" (
%SPHINXBUILD% -b latex %ALLSPHINXOPTS% %BUILDDIR%/latex
if errorlevel 1 exit /b 1
echo.
echo.Build finished; the LaTeX files are in %BUILDDIR%/latex.
goto end
)
if "%1" == "text" (
%SPHINXBUILD% -b text %ALLSPHINXOPTS% %BUILDDIR%/text
if errorlevel 1 exit /b 1
echo.
echo.Build finished. The text files are in %BUILDDIR%/text.
goto end
)
if "%1" == "man" (
%SPHINXBUILD% -b man %ALLSPHINXOPTS% %BUILDDIR%/man
if errorlevel 1 exit /b 1
echo.
echo.Build finished. The manual pages are in %BUILDDIR%/man.
goto end
)
if "%1" == "changes" (
%SPHINXBUILD% -b changes %ALLSPHINXOPTS% %BUILDDIR%/changes
if errorlevel 1 exit /b 1
echo.
echo.The overview file is in %BUILDDIR%/changes.
goto end
)
if "%1" == "linkcheck" (
%SPHINXBUILD% -b linkcheck %ALLSPHINXOPTS% %BUILDDIR%/linkcheck
if errorlevel 1 exit /b 1
echo.
echo.Link check complete; look for any errors in the above output ^
or in %BUILDDIR%/linkcheck/output.txt.
goto end
)
if "%1" == "doctest" (
%SPHINXBUILD% -b doctest %ALLSPHINXOPTS% %BUILDDIR%/doctest
if errorlevel 1 exit /b 1
echo.
echo.Testing of doctests in the sources finished, look at the ^
results in %BUILDDIR%/doctest/output.txt.
goto end
)
:end

13
setup.py Normal file
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from distutils.core import setup
setup(
name='contextlib2',
version='0.1',
py_modules=['contextlib2'],
license='PSF License',
description='Backports and enhancements for the contextlib module',
long_description=open('README.txt').read(),
author='Nick Coghlan',
author_email='ncoghlan@gmail.com',
url='http://contextlib2.readthedocs.org'
)

376
test_contextlib2.py Normal file
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"""Unit tests for contextlib.py, and other context managers."""
import sys
import unittest
from contextlib2 import * # Tests __all__
class ContextManagerTestCase(unittest.TestCase):
def test_contextmanager_plain(self):
state = []
@contextmanager
def woohoo():
state.append(1)
yield 42
state.append(999)
with woohoo() as x:
self.assertEqual(state, [1])
self.assertEqual(x, 42)
state.append(x)
self.assertEqual(state, [1, 42, 999])
def test_contextmanager_finally(self):
state = []
@contextmanager
def woohoo():
state.append(1)
try:
yield 42
finally:
state.append(999)
with self.assertRaises(ZeroDivisionError):
with woohoo() as x:
self.assertEqual(state, [1])
self.assertEqual(x, 42)
state.append(x)
raise ZeroDivisionError()
self.assertEqual(state, [1, 42, 999])
def test_contextmanager_no_reraise(self):
@contextmanager
def whee():
yield
ctx = whee()
ctx.__enter__()
# Calling __exit__ should not result in an exception
self.assertFalse(ctx.__exit__(TypeError, TypeError("foo"), None))
def test_contextmanager_trap_yield_after_throw(self):
@contextmanager
def whoo():
try:
yield
except:
yield
ctx = whoo()
ctx.__enter__()
self.assertRaises(
RuntimeError, ctx.__exit__, TypeError, TypeError("foo"), None
)
def test_contextmanager_except(self):
state = []
@contextmanager
def woohoo():
state.append(1)
try:
yield 42
except ZeroDivisionError as e:
state.append(e.args[0])
self.assertEqual(state, [1, 42, 999])
with woohoo() as x:
self.assertEqual(state, [1])
self.assertEqual(x, 42)
state.append(x)
raise ZeroDivisionError(999)
self.assertEqual(state, [1, 42, 999])
def _create_contextmanager_attribs(self):
def attribs(**kw):
def decorate(func):
for k,v in kw.items():
setattr(func,k,v)
return func
return decorate
@contextmanager
@attribs(foo='bar')
def baz(spam):
"""Whee!"""
return baz
def test_contextmanager_attribs(self):
baz = self._create_contextmanager_attribs()
self.assertEqual(baz.__name__,'baz')
self.assertEqual(baz.foo, 'bar')
@unittest.skipIf(sys.flags.optimize >= 2,
"Docstrings are omitted with -O2 and above")
def test_contextmanager_doc_attrib(self):
baz = self._create_contextmanager_attribs()
self.assertEqual(baz.__doc__, "Whee!")
class ClosingTestCase(unittest.TestCase):
# XXX This needs more work
def test_closing(self):
state = []
class C:
def close(self):
state.append(1)
x = C()
self.assertEqual(state, [])
with closing(x) as y:
self.assertEqual(x, y)
self.assertEqual(state, [1])
def test_closing_error(self):
state = []
class C:
def close(self):
state.append(1)
x = C()
self.assertEqual(state, [])
with self.assertRaises(ZeroDivisionError):
with closing(x) as y:
self.assertEqual(x, y)
1 / 0
self.assertEqual(state, [1])
class mycontext(ContextDecorator):
started = False
exc = None
catch = False
def __enter__(self):
self.started = True
return self
def __exit__(self, *exc):
self.exc = exc
return self.catch
class TestContextDecorator(unittest.TestCase):
def test_contextdecorator(self):
context = mycontext()
with context as result:
self.assertIs(result, context)
self.assertTrue(context.started)
self.assertEqual(context.exc, (None, None, None))
def test_contextdecorator_with_exception(self):
context = mycontext()
with self.assertRaises(NameError):
with context:
raise NameError('foo')
self.assertIsNotNone(context.exc)
self.assertIs(context.exc[0], NameError)
self.assertIn('foo', context.exc[1])
context = mycontext()
context.catch = True
with context:
raise NameError('foo')
self.assertIsNotNone(context.exc)
self.assertIs(context.exc[0], NameError)
def test_decorator(self):
context = mycontext()
@context
def test():
self.assertIsNone(context.exc)
self.assertTrue(context.started)
test()
self.assertEqual(context.exc, (None, None, None))
def test_decorator_with_exception(self):
context = mycontext()
@context
def test():
self.assertIsNone(context.exc)
self.assertTrue(context.started)
raise NameError('foo')
with self.assertRaises(NameError):
test()
self.assertIsNotNone(context.exc)
self.assertIs(context.exc[0], NameError)
self.assertIn('foo', context.exc[1])
def test_decorating_method(self):
context = mycontext()
class Test(object):
@context
def method(self, a, b, c=None):
self.a = a
self.b = b
self.c = c
# these tests are for argument passing when used as a decorator
test = Test()
test.method(1, 2)
self.assertEqual(test.a, 1)
self.assertEqual(test.b, 2)
self.assertEqual(test.c, None)
test = Test()
test.method('a', 'b', 'c')
self.assertEqual(test.a, 'a')
self.assertEqual(test.b, 'b')
self.assertEqual(test.c, 'c')
test = Test()
test.method(a=1, b=2)
self.assertEqual(test.a, 1)
self.assertEqual(test.b, 2)
def test_typo_enter(self):
class mycontext(ContextDecorator):
def __unter__(self):
pass
def __exit__(self, *exc):
pass
with self.assertRaises(AttributeError):
with mycontext():
pass
def test_typo_exit(self):
class mycontext(ContextDecorator):
def __enter__(self):
pass
def __uxit__(self, *exc):
pass
with self.assertRaises(AttributeError):
with mycontext():
pass
def test_contextdecorator_as_mixin(self):
class somecontext(object):
started = False
exc = None
def __enter__(self):
self.started = True
return self
def __exit__(self, *exc):
self.exc = exc
class mycontext(somecontext, ContextDecorator):
pass
context = mycontext()
@context
def test():
self.assertIsNone(context.exc)
self.assertTrue(context.started)
test()
self.assertEqual(context.exc, (None, None, None))
def test_contextmanager_as_decorator(self):
@contextmanager
def woohoo(y):
state.append(y)
yield
state.append(999)
state = []
@woohoo(1)
def test(x):
self.assertEqual(state, [1])
state.append(x)
test('something')
self.assertEqual(state, [1, 'something', 999])
# Issue #11647: Ensure the decorated function is 'reusable'
state = []
test('something else')
self.assertEqual(state, [1, 'something else', 999])
class TestCleanupManager(unittest.TestCase):
def test_no_resources(self):
with CleanupManager():
pass
def test_register(self):
expected = [
((), {}),
((1,), {}),
((1,2), {}),
((), dict(example=1)),
((1,), dict(example=1)),
((1,2), dict(example=1)),
]
result = []
def _exit(*args, **kwds):
result.append((args, kwds))
with CleanupManager() as cmgr:
for args, kwds in reversed(expected):
if args and kwds:
cmgr.register(_exit, *args, **kwds)
elif args:
cmgr.register(_exit, *args)
elif kwds:
cmgr.register(_exit, **kwds)
else:
cmgr.register(_exit)
def test_register_exit(self):
exc_raised = ZeroDivisionError
def _expect_exc(exc_type, exc, exc_tb):
self.assertIs(exc_type, exc_raised)
def _suppress_exc(*exc_details):
return True
def _expect_ok(exc_type, exc, exc_tb):
self.assertIsNone(exc_type)
self.assertIsNone(exc)
self.assertIsNone(exc_tb)
with CleanupManager() as cmgr:
cmgr.register_exit(_expect_ok)
cmgr.register_exit(_suppress_exc)
cmgr.register_exit(_expect_exc)
cmgr.register_exit(_expect_exc)
1/0
def test_enter_context(self):
class TestCM(object):
def __enter__(self):
result.append(1)
def __exit__(self, *exc_details):
result.append(3)
result = []
with CleanupManager() as cmgr:
@cmgr.register # Registered first => cleaned up last
def _exit():
result.append(4)
cmgr.enter_context(TestCM())
result.append(2)
self.assertEqual(result, [1, 2, 3, 4])
def test_close(self):
result = []
with CleanupManager() as cmgr:
@cmgr.register # Registered first => cleaned up last
def _exit():
result.append(1)
cmgr.close()
result.append(2)
self.assertEqual(result, [1, 2])
if __name__ == "__main__":
test_main()