A sample decorator the can be used on plain old functions and also on instance methods

decorators.py

class func_and_method_decorator(object):
    '''A clased based decorator that takes parameters and works on plain functions
    and instance methods'''
    def __init__(self, *args, **kwargs):
        '''The init function is called when a module where the decorator is used
        is imported. It gets passed all parameters that are given to decorator
        definition. I.e.

            @func_and_method_decorator(foo='bar')

        would result in
            kwargs = {'foo': 'bar'}
        '''
        print "func_and_method_decorator init called", args, kwargs

    def __call__(self, func):
        import functools

        print "func_and_method_decorator __call__ called"

        @functools.wraps(func)
        def decorated(*args, **kwargs):
            '''This is the function that wraps the actual function call. It is
            called when the decorated function or method is called. It can check
            or modify the parameter and/or result'''

            print "func_and_method_decorator decorated function called with", args, kwargs
            result = func(*args, **kwargs)
            print "func_and_method_decorator decorated function result is", result

            return result
        return decorated