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Handling `Literal` type in annotations. Resolves: #13672 ## Implementation Since Literals are not a fully defined type in typeshed. I used a trick to figure out when a special form is a literal. When we are inferring assignment types I am checking if the type of that assignment was resolved to typing.SpecialForm and the name of the target is `Literal` if that is the case then I am re creating a new instance type and set the known instance field to `KnownInstance:Literal`. **Why not defining a new type?** From this [issue](https://github.com/python/typeshed/issues/6219) I learned that we want to resolve members to SpecialMethod class. So if we create a new instance here we can rely on the member resolving in that already exists. ## Tests https://typing.readthedocs.io/en/latest/spec/literal.html#equivalence-of-two-literals Since the type of the value inside Literal is evaluated as a Literal(LiteralString, LiteralInt, ...) then the equality is only true when types and value are equal. https://typing.readthedocs.io/en/latest/spec/literal.html#legal-and-illegal-parameterizations The illegal parameterizations are mostly implemented I'm currently checking the slice expression and the slice type to make sure it's valid. https://typing.readthedocs.io/en/latest/spec/literal.html#shortening-unions-of-literals --------- Co-authored-by: Carl Meyer <carl@astral.sh> Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>
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748 B
Unary Operations
from typing import Literal
class Number:
def __init__(self, value: int):
self.value = 1
def __pos__(self) -> int:
return +self.value
def __neg__(self) -> int:
return -self.value
def __invert__(self) -> Literal[True]:
return True
a = Number()
reveal_type(+a) # revealed: int
reveal_type(-a) # revealed: int
reveal_type(~a) # revealed: Literal[True]
class NoDunder: ...
b = NoDunder()
+b # error: [unsupported-operator] "Unary operator `+` is unsupported for type `NoDunder`"
-b # error: [unsupported-operator] "Unary operator `-` is unsupported for type `NoDunder`"
~b # error: [unsupported-operator] "Unary operator `~` is unsupported for type `NoDunder`"