Popular recipes tagged "context_manager" but not "with_statement"

CleanupManager for with statements (Python)

2011-12-18T07:20:46-08:00

Python recipe 577981 by Nick Coghlan (contextmanager, context_manager). Revision 5.

Inspired by unittest.TestCase.addCleanup(), CleanupManager provides a means to programmatically add resources to be cleaned up when leaving a with statement. This makes it easy to use with optional resources, and those derived from sequences of inputs.

An more powerful version of this recipe with a few additional features is published under the name ContextStack as part of the contextlib2 module: http://contextlib2.readthedocs.org

This recipe is based on a suggestion originally posted by Nikolaus Rath at http://bugs.python.org/issue13585

Context manager to prevent calling code from catching exceptions (Python)

2012-06-17T09:20:56-07:00

Python recipe 577863 by Oren Tirosh (context_manager, exception).

The following context manager causes any exceptions raised inside it to print a stack trace and exit immediately. The calling scope is not given a chance to catch the exception.

Context manager for low-level redirection of stdout/stderr (Python)

2012-01-26T02:14:25-08:00

Python recipe 577564 by Greg Haskins (contextmanager, context_manager, f2py, fortran, python, redirect, stdout). Revision 3.

This context manager provides a convenient, Pythonic way to temporarily replace the file descriptors of stdout and stderr, redirecting to either os.devnull or files of your choosing. Swapping the C-level file descriptors is required when suppressing output from compiled extension modules, such as those built using F2PY. It functions equally well for pure-Python code. UPDATE: (see below).

Context manager for restoring a value (Python)

2010-01-09T07:14:06-08:00

Python recipe 576977 by George Sakkis (contextlib, context_manager). Revision 8.

Often one wants to rebind a name or modify a mutable object, perform a bunch of actions and finally restore the name/object to its original state. An example is redirecting stdout/stderr temporarily (http://www.diveintopython.org/scripts_and_streams/stdin_stdout_stderr.html). The restoring context manager shown below simplifies this pattern::

import sys

# prints in console
print "hello world!"

with restoring('sys.stdout'):
    with open('hello.txt', 'w') as sys.stdout:
        # prints in file
        print "hello world!"

# prints in console again
print "hello world!"

ChangeDirectory context manager (Python)

2009-01-24T12:41:53-08:00

Python recipe 576620 by Christophe Simonis (change, chdir, context_manager, directory). Revision 2.

A context manager that handle a temporary change of the working directory