Implementing the decorator pattern in Python

Question

I want to implement the decorator pattern in Python, and I wondered if there is a way to write a decorator that just implements the function it wants to modify, without writ

Answer 1

To complement @Alec Thomas reply. I modified his answer to follow the decorator pattern. This way you don't need to know the class you're decorating in advance.

class Decorator(object):
    def __new__(cls, decoratee):
        cls = type('decorated',
                   (cls, decoratee.__class__),
                   decoratee.__dict__)
        return object.__new__(cls)

Then, you can use it as:

class SpecificDecorator(Decorator):
    def f1(self):
        print "decorated f1"
        super(foo_decorator, self).f1()

class Decorated(object):
    def f1(self):
        print "original f1"


d = SpecificDecorator(Decorated())
d.f1()