Dynamic function docstring

Question

I\'d like to write a python function that has a dynamically created docstring. In essence for a function func() I want func.__doc__ to be a descri

Answer 1

(Python 3 solution)

You could make use of Python's duck typing to implement a dynamic string:

import time

def fn():
    pass

class mydoc( str ):
    def expandtabs( self, *args, **kwargs ):
        return "this is a dynamic strting created on {}".format( time.asctime() ).expandtabs( *args, **kwargs )

fn.__doc__ = mydoc()

help( fn )

Caveats: This assumes that the help function is calling .expandtabs to get the text from the __doc__ object, which works in Python 3.7. A more robust solution would implement the other str methods in order to have our duck continue acting like a duck even if the help method changes. Also note that our mydoc class derives from str, this is because help, somewhat atypically, enforces strong typing by asserting isinstance(thing.__doc__, str). Like all solutions this is a bit hacky, but whether this is a problem largely depends on the full project requirements.