如何在Python中使用doctest测试装饰函数？

Question

我正在使用一个装饰器：

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()

还有一个函数：

@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)

但是当使用doctest模块（python mycode.py -v）时：

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

Python无法在doc-string中找到测试。我知道这是装饰器的问题。但是我该如何解决呢？

PS：functools.update_wrapper(self, func)无效！

- Farshid Ashouri

---

你尝试过 functools.wraps 装饰器吗？https://dev59.com/fXVC5IYBdhLWcg3wZwJT - Andrew Gorcester

相关票务 - shx2

@AndrewGorcester 我看了那个链接，谢谢。但我想知道如何在装饰器类中使用wraps？ - Farshid Ashouri

Answer 1

我们可以通过使用一个装饰器 memo 来绕过这个问题，该装饰器返回一个函数而不是一个类实例：

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()

- unutbu

---

memo(f) 修改 f.__doc__ 会怎么样？修改后的文档字符串能通过 doctest 吗？我有一个类似的谜题，但是涉及到类而不是函数：https://stackoverflow.com/q/74694520/557937 - Dima Pasechnik