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Add missing dunder attributes for TypeAliasType instances #470
Add missing dunder attributes for TypeAliasType instances #470
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From what I see In 3.9 it will raise an TypeError in belows test as it tries to subscript the With def test_callable_with_concatenate(self):
P = ParamSpec('P')
CallableP = TypeAliasType("CallableP", Callable[P, Any], type_params=(P,))
callable_concat = CallableP[Concatenate[int, P]]
self.assertEqual(callable_concat.__parameters__, (P,))
concat_usage = callable_concat[str] # <-- will fail for 3.9 with GenericAlias |
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Thanks! I pushed a slightly different solution to your PR branch (using a _GenericAlias
subclass) so that all the tests would pass on py38 and py39 as well. Your tests were fantastic; they really helped to see all aspects of the problem!
Adresses: #449
As @JelleZijlstra mentioned that GenericAlias can be used to address #469.
GenericAlias
seems promising, however I am not sure what greater underlying changes this swap could maybe cause.Currently I am still tracing some errors and I want to make sure I am not regressing some cases that currently are not covered by tests. This is also a reason this is currently only used for 3.10+.
See below I think using it in 3.9 will cause more harm than benefits.