class_method.py

"""
method和function是一回事，classmethod则是另一个类型，所有对类中方法的调用都是经过了descriptor变换成bounded method对象，最后再访问
类型为<class 'method-wrapper'>的__call__属性
这么看来其实也是classmethod，method，function都是统一到了descriptor对象，
"""
from functools import wraps


class my_classmethod:
    def __init__(self, func):
        wraps(func)(self)

    def __get__(self, instance, owner):
        return self.__wrapped__.__get__(owner, owner)


class M:
    @my_classmethod
    def f(cls):
        print(cls)
        return cls

    @classmethod
    def f1(self):
        print(self)
        return self

    print(type(f))
    print(type(f1))

    def f2(self): pass

    global F
    global F2
    global F1
    F = f
    F2 = f2
    F1 = f1
    print(type(f2))


M.f1()
M().f1()

assert M.f2 is F2
assert M.f is not F
assert M().f1 is not F1

assert M.f() is M

assert M().f() is M
assert M().f() == M