Create annotated function preserving original function intact

placfun.py

""" A study, how to create plac annotated command line script from bare function
preserving original function intact.

This is sometime needed, when the same function is used for call e.g. by a celery, 
and for manual testing it is handy to have it in command line version.

Usually, the code (producing only annotated command line tool) looks like::

    import plac

    @plac.annotations(
        name="your name", 
        surname="your surname"
    )
    def main(name, surname):
        "have a fun with name and surname decorated"
        print name, surname

    if __name__ == "__main__":
        plac.call(main)

Try from command line::

    $ python placfun.py -h
    usage: placfun.py [-h] name surname

    have a fun with name and surname decorated

    positional arguments:
      name        your name
      surname     your surname

    optional arguments:
      -h, --help  show this help message and exit

and with params::

    $ python placfun.py Jan Vlcinsky
    Jan Vlcinsky

Following code does the same, but keeps the original "fun" function intact,
so that other importers do not have to use the decorated version.

For decorating explained see:: http://freepythontips.wordpress.com/2013/10/10/all-about-decorators-in-python/
"""
import plac

def fun(name, surname):
    """have a fun with name and surname decorated"""
    print name, surname

main = plac.annotations(
    name="your name", 
    surname="your surname"
) (fun)


if __name__ == "__main__":
    plac.call(main)