在Python中实现装饰器模式

Question

我想在Python中实现装饰器模式，我想知道是否有一种方法可以编写一个装饰器，该装饰器仅实现要修改的功能，而无需为所有转发给装饰对象的功能编写样板。像这样：

class foo(object):
    def f1(self):
        print "original f1"
    def f2(self):
        print "original f2"

class foo_decorator(object):
    def __init__(self, decoratee):
        self._decoratee = decoratee
    def f1(self):
        print "decorated f1"
        self._decoratee.f1()
    def f2(self):              # I would like to leave that part out
        self._decoratee.f2()

我想将呼叫自动foo_decorator.f2转发到decoratee.f2。有没有一种方法可以将所有未实现的函数调用转发给的通用方法decoratee？

Answer 1

您可以使用__getattr__：

class foo(object):
    def f1(self):
        print "original f1"
    def f2(self):
        print "original f2"

class foo_decorator(object):
    def __init__(self, decoratee):
        self._decoratee = decoratee
    def f1(self):
        print "decorated f1"
        self._decoratee.f1()
    def __getattr__(self, name):
        return getattr(self._decoratee, name)

u = foo()
v = foo_decorator(u)
v.f1()
v.f2()