9.8. functools - Higher order functions and operations on callable objects - P... - The Diigo Meta page

• 20 Oct 09
  

  Benx Shen

  python code

  • functools.partial(func, *args, **keywords)¶

    
    

    Return a new partial object which when called will behave like func
    called with the positional arguments args and keyword arguments keywords. If
    more arguments are supplied to the call, they are appended to args. If
    additional keyword arguments are supplied, they extend and override keywords.
    Roughly equivalent to:

    
    

    def partial(func, *args, **keywords):
        def newfunc(*fargs, **fkeywords):
            newkeywords = keywords.copy()
            newkeywords.update(fkeywords)
            return func(*(args + fargs), **newkeywords)
        newfunc.func = func
        newfunc.args = args
        newfunc.keywords = keywords
        return newfunc
    

  • functools.wraps(wrapped, assigned=WRAPPER_ASSIGNMENTS, updated=WRAPPER_UPDATES)¶

    
    

    This is a convenience function for invoking partial(update_wrapper,
    wrapped=wrapped, assigned=assigned, updated=updated) as a function decorator
    when defining a wrapper function. For example:

    
    

    >>> from functools import wraps
    >>> def my_decorator(f):
    ...     @wraps(f)
    ...     def wrapper(*args, **kwds):
    ...         print('Calling decorated function')
    ...         return f(*args, **kwds)
    ...     return wrapper
    ...
    >>> @my_decorator
    ... def example():
    ...     """Docstring"""
    ...     print('Called example function')
    ...
    >>> example()
    Calling decorated function
    Called example function
    >>> example.__name__
    'example'
    >>> example.__doc__
    'Docstring'
    

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