クラスを使わずカウンターを作ってみる

cntr.py

# -*- coding:utf-8 -*-
from collections import defaultdict
from functools import partial

def counter(*keys):
    """クラスを使わずにカウンターを作る。
    >>> cnt = counter("foo", "bar", "baz")
    >>> cnt.foo()
    >>> cnt.foo()
    >>> cnt.bar()
    >>> cnt.bar()
    >>> cnt.bar()
    >>> cnt("baz", 7)
    >>> cnt.baz()
    >>> cnt.all()["foo"]
    2
    >>> cnt.all()["bar"]
    3
    >>> cnt.all()["baz"]
    8
    >>> cnt.reset("foo")
    >>> cnt.value("foo")
    0
    >>> cnt.value("bar")
    3
    >>> cnt.resetall()
    >>> cnt.value("bar")
    0
    >>> cnt2 = counter("foo", "bar", "baz")
    >>> cnt2.foo()
    >>> cnt2.value("foo")
    1
    >>> cnt.value("foo")
    0
    """
    nums = defaultdict(int)
    def count(k, num=None):
        if num is None:
            nums[k] += 1
        else:
            nums[k] = num
    count.all = lambda: dict(nums)
    count.value = lambda k: nums[k]
    count.reset = lambda k: count(k, 0)
    count.resetall = lambda: nums.clear()
    for key in (x for x in keys if not hasattr(count, x)):
        # ここでpartialを使わずlambdaを使うとはまる。
        setattr(count, key, partial(count, k=key))
    return count

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