celery/celery/utils/functional.py

"""Functional utilities for Python 2.4 compatibility."""
# License for code in this file that was taken from Python 2.5.

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### Begin from Python 2.5 functools.py ########################################

# Summary of changes made to the Python 2.5 code below:
#   * swapped ``partial`` for ``curry`` to maintain backwards-compatibility
#     in Django.
#   * Wrapped the ``setattr`` call in ``update_wrapper`` with a try-except
#     block to make it compatible with Python 2.3, which doesn't allow
#     assigning to ``__name__``.

# Copyright (c) 2001, 2002, 2003, 2004, 2005, 2006, 2007 Python Software
# Foundation. All Rights Reserved.

###############################################################################

# update_wrapper() and wraps() are tools to help write
# wrapper functions that can handle naive introspection

def _compat_curry(fun, *args, **kwargs):
    """New function with partial application of the given arguments
    and keywords."""

    def _curried(*addargs, **addkwargs):
        return fun(*(args+addargs), **dict(kwargs, **addkwargs))
    return _curried


try:
    from functools import partial as curry
except ImportError:
    curry = _compat_curry

WRAPPER_ASSIGNMENTS = ('__module__', '__name__', '__doc__')
WRAPPER_UPDATES = ('__dict__',)
def _compat_update_wrapper(wrapper, wrapped, assigned=WRAPPER_ASSIGNMENTS,
        updated=WRAPPER_UPDATES):
    """Update a wrapper function to look like the wrapped function

       wrapper is the function to be updated
       wrapped is the original function
       assigned is a tuple naming the attributes assigned directly
       from the wrapped function to the wrapper function (defaults to
       functools.WRAPPER_ASSIGNMENTS)
       updated is a tuple naming the attributes off the wrapper that
       are updated with the corresponding attribute from the wrapped
       function (defaults to functools.WRAPPER_UPDATES)

    """
    for attr in assigned:
        try:
            setattr(wrapper, attr, getattr(wrapped, attr))
        except TypeError: # Python 2.3 doesn't allow assigning to __name__.
            pass
    for attr in updated:
        getattr(wrapper, attr).update(getattr(wrapped, attr))
    # Return the wrapper so this can be used as a decorator via curry()
    return wrapper

try:
    from functools import update_wrapper
except ImportError:
    update_wrapper = _compat_update_wrapper


def _compat_wraps(wrapped, assigned=WRAPPER_ASSIGNMENTS,
        updated=WRAPPER_UPDATES):
    """Decorator factory to apply update_wrapper() to a wrapper function

    Returns a decorator that invokes update_wrapper() with the decorated
    function as the wrapper argument and the arguments to wraps() as the
    remaining arguments. Default arguments are as for update_wrapper().
    This is a convenience function to simplify applying curry() to
    update_wrapper().

    """
    return curry(update_wrapper, wrapped=wrapped,
                 assigned=assigned, updated=updated)

try:
    from functools import wraps
except ImportError:
    wraps = _compat_wraps

### End from Python 2.5 functools.py ##########################################