Add support for type aliases using the "type" keyword#287
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Kyoya2 wants to merge 2 commits intokonradhalas:masterfrom
Open
Add support for type aliases using the "type" keyword#287Kyoya2 wants to merge 2 commits intokonradhalas:masterfrom
Kyoya2 wants to merge 2 commits intokonradhalas:masterfrom
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Kyoya2
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Oct 18, 2025
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| if version_info >= (3, 14): | ||
| @cache | ||
| def extract_type_alias(type_: TypeAliasType) -> Type: | ||
| return type_.evaluate_value() | ||
| else: | ||
| @cache | ||
| def extract_type_alias(type_: TypeAliasType) -> Type: | ||
| return type_.__value__ |
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This if statement is technically unnecessary, since the else branch will always work. However, I believe that it's best practice to avoid accessing "internal" attributes such as __value__ when possible. I can get rid of it if desired.
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Starting from Python 3.12, it's possible to define a type alias using the following syntax:
This creates a
typing.TypeAliasTypeobject under the nameMyAlias.I added support for such type aliases, along with some tests.
I should note that some of the new tests (like
test_is_type_alias) should've been added totests/test_types.py. Instead, I placed them intests/core/test_type_alias.py, because using the "type" keyword on Python versions older than 3.12 would raise aSyntaxErrorwhen the file is evaluated. Which is why the entire filetests/core/test_type_alias.pyis excluded from testing on those older versions.