Python 3.12+typingterm

typing.TypeAliasType

generics and parameters

The type of objects created by the `type X = ...` statement (type aliases; 3.12+).

Syntax

type X = int  # X — экземпляр TypeAliasType

Instances usually come from the type X = ... statement (PEP 695); the TypeAliasType(name, value) constructor arrived in the same 3.12 and is for creating an alias at run time; versions before 3.12 take it from typing_extensions. With the type statement the right-hand side is evaluated lazily — only when you access X.__value__ — so an alias can reference names not yet defined, or itself for recursive types, without quoting them as strings.

Examples

from typing import TypeAliasType
type MyInt = int
print(isinstance(MyInt, TypeAliasType))   # → True
print(MyInt.__name__)   # → MyInt
print(MyInt.__value__)   # → <class 'int'>
print(MyInt is int)   # → False
type Vector = list[float]
print(Vector.__value__)   # → list[float]

See also

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