Source code for metatools.monkeypatch

from __future__ import absolute_import

import logging
import os
import errno
import sys

log = logging.getLogger(__name__)

[docs]def patch(to_patch, name=None, must_exist=True, max_version=None): """Monkey patching decorator. :param to_patch: The object to patch. :param str name: The attribute of the object to patch; defaults to name of the patch function. :param bool must_exist: Must the original exist for the patch to be applied? :param tuple max_version: The maximum Python version to apply this patch to. :return: A decorator which takes a function and applies the patch, returning the patched version. Usage:: # Patch os.listdir to return all lowercase. @patch(os) def listdir(original, path): return [x.lower() for x in original(path)] # It is patched in place. os.listdir('.') # The new function still refers to the original. listdir('.') # Patch chflags to do nothing in Python up to 2.6. @patch(os, 'chflags', max_version=(2, 6)) def patched_chflags(func, *args, **kwargs): pass """ # Build a decorator which will apply the patch. def _decorator(func): # Get the name we are replacing. attrname = name or func.__name__ # The thing we are replacing. func.__monkeypatched__ = original = getattr(to_patch, attrname, None) # A function to actually call the patch. def _patch_wrapper(*args, **kwargs): return func(func.__monkeypatched__, *args, **kwargs) # Make it look like the original. _patch_wrapper.__name__ = original.__name__ if original else func.__name__ _patch_wrapper.__doc__ = '\n\n--- Monkey-Patched ---\n\n'.join(filter(None, [ func.__doc__, original.__doc__ if original else 'Original %r does not exist.' % attrname, ])) or None # Bail if we don't want to apply the patch. if max_version and sys.version[:len(max_version)] > max_version: log.log(5, 'not patching %s.%s with %s.%s; version > %r', getattr(to_patch, '__name__', to_patch), attrname, getattr(func, '__module__', 'unknown'), getattr(func, '__name__', func), max_version, ) return _patch_wrapper # Bail if it doesn't exist. if must_exist and not original: log.log(5, 'not patching %s.%s with %s.%s; original does not exist', getattr(to_patch, '__name__', to_patch), attrname, getattr(func, '__module__', 'unknown'), getattr(func, '__name__', func), ) return _patch_wrapper # Install the patch. log.log(5, 'patching %r.%s with %r', to_patch, attrname, func) setattr(to_patch, attrname, _patch_wrapper) # Return the *patched* function. return _patch_wrapper # Return the patch building decorator. return _decorator
if __name__ == '__main__': import os @patch(os) def listdir(func, path): return [x.upper() for x in func(path)] print '\n'.join(os.listdir('.'))
Read the Docs v: latest
On Read the Docs
Project Home

Free document hosting provided by Read the Docs.