docstring show under decorator

http://stackoverflow.com/questions/3865254/about-python-doc-docstring/3865321#3865321

functools.wraps(wrapped[, assigned][, updated])¶

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'

Without the use of this decorator factory, the name of the example function would have been 'wrapper', and the docstring of the original example() would have been lost.