recipe-577993.py 文件源码

def __get__(self, instance, cls):
        """Descriptor protocol support.

        This makes an instance of this class function correctly when it
        is used to decorate a method on a user-defined class. If called
        as a bound method, we store the decorated function in the instance
        dictionary, so we will not be called again for that instance. If
        called as an unbound method, we store a reference to the decorated
        function internally and use it on future unbound method calls.
        """
        if instance:
            deco = instancemethod(self._decorated(cls, instance), instance, cls)
            # This prevents us from being called again for this instance
            setattr(instance, self._func.__name__, deco)
        elif cls:
            if not self.__clsfunc:
                self.__clsfunc = instancemethod(self._decorated(cls), None, cls)
            deco = self.__clsfunc
        else:
            raise ValueError("Must supply instance or class to descriptor.")
        return deco