Can an __init__ automatically execute code after calling super?

Question

I have something like this:

class SuperClass(object):
    def __init__(self):
        # initialization stuff

    def always_do_this_last(self):
        # cleanup stuff


class SubClass(SuperClass):
    def __init__(self):
        super().__init__()
        # intermediate stuff
        self.always_do_this_last()

Is it possible to automatically call that last line? Every subclass of SuperClass needs perform the cleanup.

Answer 1

Instead of overriding __init__, define a method that SuperClass.__init__ will call.

class SuperClass(object):
    def __init__(self):
        # do some stuff
        self.child_init()
        self.cleanup()

    def cleanup():
        ...

    def child_init(self):
        pass


class SubClass(SuperClass):
    def child_init(self):
        ...

You can define SuperClass.__init_subclass__ to ensure child_init is overriden, or use the abc module to make SuperClass.child_init an abstract method

Answer 2

One option could be to use a method that the subclasses could override without overriding __init__(). Maybe like this:

class SuperClass:
    def __init__(self):
        # initialization stuff
        self.setup_subclass()
        self.always_do_this_last()

    def setup_subclass(self):
        pass

    def always_do_this_last(self):
        # cleanup stuff

class SubClass(SuperClass):
    def setup_subclass(self):
        # intermediate stuff

Would that work for you?