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Have namedtuple __replace__ return Self #17475

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Merged
merged 6 commits into from
Jul 3, 2024
Merged

Have namedtuple __replace__ return Self #17475

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d2dc190
Have nametuple `__replace__` return self
max-muoto Jul 3, 2024
a8aaef3
Merge branch 'master' into have-named-tuple-replace-return-self
max-muoto Jul 3, 2024
90d53a7
Test generics
max-muoto Jul 3, 2024
4f80456
Fix
max-muoto Jul 3, 2024
a2a02de
Tweak
max-muoto Jul 3, 2024
bbed523
Merge branch 'master' into have-named-tuple-replace-return-self
max-muoto Jul 3, 2024
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4 changes: 3 additions & 1 deletion mypy/semanal_namedtuple.py
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Original file line number Diff line number Diff line change
Expand Up @@ -57,6 +57,7 @@
TYPED_NAMEDTUPLE_NAMES,
AnyType,
CallableType,
Instance,
LiteralType,
TupleType,
Type,
Expand Down Expand Up @@ -631,9 +632,10 @@ def add_method(
args=[Argument(var, var.type, EllipsisExpr(), ARG_NAMED_OPT) for var in vars],
)
if self.options.python_version >= (3, 13):
type_vars = [tv for tv in info.defn.type_vars]
add_method(
"__replace__",
ret=None,
ret=Instance(info, type_vars),
args=[Argument(var, var.type, EllipsisExpr(), ARG_NAMED_OPT) for var in vars],
)

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16 changes: 15 additions & 1 deletion test-data/unit/check-namedtuple.test
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Expand Up @@ -1407,9 +1407,23 @@ from typing import NamedTuple
class A(NamedTuple):
x: int

A(x=0).__replace__(x=1)
replaced = A(x=0).__replace__(x=1)
reveal_type(replaced) # N: Revealed type is "__main__.A"

A(x=0).__replace__(x="asdf") # E: Argument "x" to "__replace__" of "A" has incompatible type "str"; expected "int"
A(x=0).__replace__(y=1) # E: Unexpected keyword argument "y" for "__replace__" of "A"

from typing import TypeVar, Generic

T = TypeVar("T")

class GenericA(NamedTuple, Generic[T]):
x: T

replaced_2 = GenericA(x=0).__replace__(x=1)
reveal_type(replaced_2) # N: Revealed type is "__main__.GenericA"
GenericA(x=0).__replace__(x="abc") # E: Argument "x" to "__replace__" of "GenericA" has incompatible type "str"; expected "int"
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It's specialized, but the generic isn't in the revealed type which is odd.

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I think that's how mypy generally works:

% mypy -c 'x: list[str] = []; x.append(1)'
<string>:1: error: Argument 1 to "append" of "list" has incompatible type "int"; expected "str"  [arg-type]

Agree this is potentially confusing but it's not something that should be changed in this PR.

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Ah I see, makes sense - let me bring this out of draft in that case.


[builtins fixtures/tuple.pyi]
[typing fixtures/typing-namedtuple.pyi]

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