In Python, how do I indicate I'm overriding a method?

Question

In Java, for example, the @Override annotation not only provides compile-time checking of an override but makes for excellent self-documenting code.

I'm just looking for documentation (although if it's an indicator to some checker like pylint, that's a bonus). I can add a comment or docstring somewhere, but what is the idiomatic way to indicate an override in Python?

Answer 1

Based on this and fwc:s answer I created a pip installable package https://github.com/mkorpela/overrides

From time to time I end up here looking at this question. Mainly this happens after (again) seeing the same bug in our code base: Someone has forgotten some "interface" implementing class while renaming a method in the "interface"..

Well Python ain't Java but Python has power -- and explicit is better than implicit -- and there are real concrete cases in the real world where this thing would have helped me.

So here is a sketch of overrides decorator. This will check that the class given as a parameter has the same method (or something) name as the method being decorated.

If you can think of a better solution please post it here!

def overrides(interface_class):
    def overrider(method):
        assert(method.__name__ in dir(interface_class))
        return method
    return overrider

It works as follows:

class MySuperInterface(object):
    def my_method(self):
        print 'hello world!'


class ConcreteImplementer(MySuperInterface):
    @overrides(MySuperInterface)
    def my_method(self):
        print 'hello kitty!'

and if you do a faulty version it will raise an assertion error during class loading:

class ConcreteFaultyImplementer(MySuperInterface):
    @overrides(MySuperInterface)
    def your_method(self):
        print 'bye bye!'

>> AssertionError!!!!!!!