python使用反射来实现通过字符串调用函数

class A:
    def a(self, params):
        print("I from a, params is {}".format(params))

    @staticmethod
    def b(params):
        print("I from b, params is {}".format(params))

    @classmethod
    def c(cls, params):
        print("I from c, params is {}".format(params))


def d(params):
    print("I from d, params is {}".format(params))


demo = A()
getattr(demo, "a")("a")
getattr(A, "b")("b")
getattr(A, "c")("c")

setattr(demo, "d", d)
getattr(demo, "d")("d")