Question

Is it possible to create a decorator which can be __init__‘d with a set of arguments, then later have methods called with other arguments?

For instance:

from foo import MyDecorator

bar = MyDecorator(debug=True)

@bar.myfunc(a=100)
def spam():
    pass

@bar.myotherfunc(x=False)
def eggs():
    pass

If this is possible, can you provide a working example?

Answer 1

Sure, a decorator is just a function which accepts a function and returns a function. There’s no reason that function can’t be (or, if you have arguments, can’t be returned by) an instance method. Here’s a really trivial example (because I’m not sure what exactly you’d be trying to do with this):

class MyDecorator(object):
    def __init__(self, debug):
        self.debug = debug
    def myfunc(self, a):
        def decorator(fn):
            def new_fn():
                if self.debug:
                    print a
                fn()
            return new_fn
        return decorator
    def myotherfunc(self, x):
        def decorator(fn):
            def new_fn():
                if self.debug:
                    print x
                fn()
            return new_fn
        return decorator

Like I said, I can’t think of a use case for this off the top of my head. But I’m sure they’re out there.