How to use doctest with a decorated function in python?

Question

I am using a decorator:

class Memoized(object):

    __cache = {}

    def __init__(self, func):
        self.func = func
        key = (func.__module__, func.__name__)
        # print key
        if key not in self.__cache:
            self.__cache[key] = {}
        self.mycache = self.__cache[key]

    def __call__(self, *args):
        try:
            return self.mycache[args]
        except KeyError:
            value = self.func(*args)
            self.mycache[args] = value
            return value
        except TypeError:
            return self.func(*args)

    def __get__(self, obj, objtype):
       return functools.partial(self.__call__, obj)

    def reset(self):
        for v in self.__cache.itervalues():
            v.clear()

and a function:

@Memoized
def is_tile_inside_border(x, y, z, border):
    '''Checks if a tile is inside border or not
    >>> is_tile_inside_border(85,53,7,'iran')
    3
    >>> is_tile_inside_border(85,15,7,'iran')
    0
    '''
    binary_data = get_border_binary(border, z)
    return isInside((x, y), binary_data)

But when using doctest module (python mycode.py -v):

if __name__ == '__main__':
    import doctest
    doctest.testmod()

Python can't find the test in doc-string. I know that is a problem with decorator. But how can I fix it?

PS: functools.update_wrapper(self, func) is not working!

Have you tried the `functools.wraps` decorator? http://stackoverflow.com/questions/308999/what-does-functools-wraps-do — Andrew Gorcester, May 10 '14 at 19:16
@AndrewGorcester I studied the link, thank you. But I am woundering how can I use *wraps* in a decorator CLASS? — Farshid Ashouri, May 10 '14 at 19:27

score 4 · Accepted Answer · answered May 10 '14 at 19:21

How about we side-step the problem by using a memo decorator which returns a function instead of a class instance:

import functools

def decorator(d):
    """Make function d a decorator: d wraps a function fn.
    Authors: Peter Norvig and Darius Bacon"""
    def _d(fn):
        return functools.update_wrapper(d(fn), fn)
    functools.update_wrapper(_d, d)
    return _d

@decorator
def memo(f):
    # by Peter Norvig
    """Decorator that caches the return value for each call to f(args).
    Then when called again with same args, we can just look it up."""
    cache = {}

    def _f(*args):
        try:
            return cache[args]
        except KeyError:
            cache[args] = result = f(*args)
            return result
        except TypeError:
            # some element of args can't be a dict key
            return f(*args)
    _f.cache = cache
    return _f

@memo
def is_tile_inside_border(x, y, z, border):
    '''Checks if a tile is inside border or not
    >>> is_tile_inside_border(85,53,7,'iran')
    3
    >>> is_tile_inside_border(85,15,7,'iran')
    0
    '''
    # binary_data = get_border_binary(border, z)
    # return isInside((x, y), binary_data)
    return True

class Foo(object):
    @memo
    def bar(self, x):
        """
        >>> Foo().bar(1)
        2
        """
        return x

if __name__ == '__main__':
    import doctest
    doctest.testmod()

How about `memo(f)` also modifying `f.__doc__` ? Would the doctests be running on the modified docstrings? I have a similar puzzle,but with classes rather than functions: https://stackoverflow.com/q/74694520/557937 — Dima Pasechnik, Dec 06 '22 at 00:29

How to use doctest with a decorated function in python?

1 Answers1