mirror of
https://github.com/astral-sh/ruff
synced 2026-01-23 22:40:48 -05:00
b2a0d68d70
We now support class patterns in a match statement, adding a narrowing constraint that within the body of that match arm, we can assume that the subject is an instance of that class. --------- Co-authored-by: Carl Meyer <carl@astral.sh> Co-authored-by: Micha Reiser <micha@reiser.io>
950 B
950 B
Narrowing for match statements
Single match pattern
def _(flag: bool):
x = None if flag else 1
reveal_type(x) # revealed: None | Literal[1]
y = 0
match x:
case None:
y = x
reveal_type(y) # revealed: Literal[0] | None
Class patterns
def get_object() -> object: ...
class A: ...
class B: ...
x = get_object()
reveal_type(x) # revealed: object
match x:
case A():
reveal_type(x) # revealed: A
case B():
# TODO could be `B & ~A`
reveal_type(x) # revealed: B
reveal_type(x) # revealed: object
Class pattern with guard
def get_object() -> object: ...
class A:
def y() -> int: ...
class B: ...
x = get_object()
reveal_type(x) # revealed: object
match x:
case A() if reveal_type(x): # revealed: A
pass
case B() if reveal_type(x): # revealed: B
pass
reveal_type(x) # revealed: object