1 """functools.py - Tools for working with functions and callable objects

     2 """

     3 # Python module wrapper for _functools C module

     4 # to allow utilities written in Python to be added

     5 # to the functools module.

     6 # Written by Nick Coghlan <ncoghlan at gmail.com>

     7 #   Copyright (C) 2006 Python Software Foundation.

     8 # See C source code for _functools credits/copyright

     9 

    10 from _functools import partial

    11 

    12 # update_wrapper() and wraps() are tools to help write

    13 # wrapper functions that can handle naive introspection

    14 

    15 WRAPPER_ASSIGNMENTS = ('__module__', '__name__', '__doc__')

    16 WRAPPER_UPDATES = ('__dict__',)

    17 def update_wrapper(wrapper,

    18                    wrapped,

    19                    assigned = WRAPPER_ASSIGNMENTS,

    20                    updated = WRAPPER_UPDATES):

    21     """Update a wrapper function to look like the wrapped function

    22 

    23        wrapper is the function to be updated

    24        wrapped is the original function

    25        assigned is a tuple naming the attributes assigned directly

    26        from the wrapped function to the wrapper function (defaults to

    27        functools.WRAPPER_ASSIGNMENTS)

    28        updated is a tuple naming the attributes off the wrapper that

    29        are updated with the corresponding attribute from the wrapped

    30        function (defaults to functools.WRAPPER_UPDATES)

    31     """

    32     for attr in assigned:

    33         setattr(wrapper, attr, getattr(wrapped, attr))

    34     for attr in updated:

    35         getattr(wrapper, attr).update(getattr(wrapped, attr, {}))

    36     # Return the wrapper so this can be used as a decorator via partial()

    37     return wrapper

    38 

    39 def wraps(wrapped,

    40           assigned = WRAPPER_ASSIGNMENTS,

    41           updated = WRAPPER_UPDATES):

    42     """Decorator factory to apply update_wrapper() to a wrapper function

    43 

    44        Returns a decorator that invokes update_wrapper() with the decorated

    45        function as the wrapper argument and the arguments to wraps() as the

    46        remaining arguments. Default arguments are as for update_wrapper().

    47        This is a convenience function to simplify applying partial() to

    48        update_wrapper().

    49     """

    50     return partial(update_wrapper, wrapped=wrapped,

    51                    assigned=assigned, updated=updated)