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What is Python 3.12's new type parameter syntax (type, generic classes)?

Q: What is Python 3.12's new type parameter syntax (type, generic classes)?

PEP 695 (3.12) adds `type Alias[T] = ...`, `def f[T](x: T) -> T`, and `class Stack[T]:` — inline type params without `TypeVar` declarations. TypeVar = TypeVar('T') def f[T](x: T) | | Pre-3.12 | 3.12+ (PEP 695) | |---|---|---| | Func generic | `T = TypeVar('T'); def f(x: T) -> T` | `def f[T](x: T) -> T` | | Class generic | `class C(Generic[T]):` | `class C[T]:` | | Type alias | `Alias: TypeAlias = list[int]` | `type Alias[T] = list[T]` | | Scope | Module global | Lexically scoped to def/class | Old `TypeVar` still wor

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PEP 695 — type, class Foo[T], and def f[T]() replacing TypeVar boilerplate.

typinggenericspython3.12

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PEP 695 (3.12) adds type Alias[T] = ..., def f[T](x: T) -> T, and class Stack[T]: — inline type params without TypeVar declarations.

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