Python 3.9 - Passing Method When Initialising Static Variable

Question

I was hoping to be able to do this:

class C:
    def __init__(self, foo:Callable):
        self._foo = foo

class D:

    bar:'C' = C(D.ping) # Unresolved reference 'D'
    
    # I also tried this;
    # bar:'C' = C(ping) # Unresolved reference 'ping'

    def __init__(self):
        ...

    def ping(self, pong:str):
        ...

I was surprised this didn't work. Is this not possible?

You can obviously do this:

...

class E:
    bar:'C' = C(D.ping)
    
    def __init__ ... #etc

This is a very similar question: Calling class staticmethod within the class body?

But perhaps different because they are trying to call a static method, while I am trying to pass it as a parameter.

Answer 1

As a workaround, you could put bar definition after ping definition:

class D:
    print(locals())

    def __init__(self):
        ...

    def ping(self, pong: str):
        ...

    print(locals())
    bar: 'C' = C(ping)

{'__module__': '__main__', '__qualname__': 'D', '__annotations__': {}}
{'__module__': '__main__', '__qualname__': 'D', '__annotations__': {}, '__init__': <function D.__init__ at 0x7f18f5de0e50>, 'ping': <function D.ping at 0x7f18f5de0ee0>}