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.

alex_noname · Accepted Answer · 2020-12-16 07:52:13Z

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>}

answered Dec 16, 2020 at 7:52

alex_noname

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1 Comment

James Izzard Over a year ago

That's interesting. I didn't think of that.

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