object.__init__() takes no parameters in test_inheritance

[slozier]

In IronPython.test_inheritance there are tests which are similar to:

import System

class test(System.Collections.Generic.List[System.Int32]):
    def __init__(self):
        super().__init__(1)

test()

which fail with:

TypeError: object.__init__() takes no parameters

These tests worked with IronPython 2 and raised a DeprecationWarning. I'm not entirely sure what the purpose of having the super().__init__ calls on a .NET class (which doesn't define __init__). I think having it throw TypeError is correct and the tests should be fixed.

[BCSharp]

I agree that TypeError in such case is sensible but I think this the whole picture is a little bit trickier.

.NET classes do define __init__ that takes unlimited number of arguments and does nothing, but only if there is no __init__ in the derived class (see the doctext on InstanceOps). I think the reason was to make a smooth and regular Python object construction using the __new__/__init__ progression. But in practice, I see no good reason to call super().__init__ in classes derived from .NET classes. However, from the type system viewpoint, it is inconsistent: I can do:

t = System.Collections.Generic.List[System.Int32](8)
t.__init__(1)

I can also call super().__init__() in class test, but not super().__init__(1) as you have discovered.

[slozier]

Hmm, interesting that instances of .NET types have an __init__ that doesn't appear on the type. Anyway, getting a headache thinking about this so will leave it for the future. 😃

Disabled some tests related to this in https://github.com/IronLanguages/ironpython3/pull/1414