8795d9f0cb
## Summary This is another small refactor for https://github.com/astral-sh/ruff/pull/21445 that splits the single `paramspec.md` into `generics/legacy/paramspec.md` and `generics/pep695/paramspec.md`. ## Test Plan Make sure that all mdtests pass.
1.4 KiB
1.4 KiB
PEP 695 ParamSpec
ParamSpec was introduced in Python 3.12 while the support for specifying defaults was added in
Python 3.13.
[environment]
python-version = "3.13"
Definition
def foo1[**P]() -> None:
reveal_type(P) # revealed: typing.ParamSpec
Bounds and constraints
ParamSpec, when defined using the new syntax, does not allow defining bounds or constraints.
TODO: This results in a lot of syntax errors mainly because the AST doesn't accept them in this position. The parser could do a better job in recovering from these errors.
# error: [invalid-syntax]
# error: [invalid-syntax]
# error: [invalid-syntax]
# error: [invalid-syntax]
# error: [invalid-syntax]
# error: [invalid-syntax]
def foo[**P: int]() -> None:
# error: [invalid-syntax]
# error: [invalid-syntax]
pass
Default
The default value for a ParamSpec can be either a list of types, ..., or another ParamSpec.
def foo2[**P = ...]() -> None:
reveal_type(P) # revealed: typing.ParamSpec
def foo3[**P = [int, str]]() -> None:
reveal_type(P) # revealed: typing.ParamSpec
def foo4[**P, **Q = P]():
reveal_type(P) # revealed: typing.ParamSpec
reveal_type(Q) # revealed: typing.ParamSpec
Other values are invalid.
# error: [invalid-paramspec]
def foo[**P = int]() -> None:
pass