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## Summary https://github.com/astral-sh/ty/issues/111 adds support for the new `copy.replace` and `__replace__` protocol [added in 3.13](https://docs.python.org/3/whatsnew/3.13.html#copy) - docs: https://docs.python.org/3/library/copy.html#object.__replace__ - some discussion on pyright/mypy implementations: https://discuss.python.org/t/dataclass-transform-and-replace/69067 ### Burndown - [x] add tests - [x] implement `__replace__` - [ ] [collections.namedtuple()](https://docs.python.org/3/library/collections.html#collections.namedtuple) - [x] [dataclasses.dataclass](https://docs.python.org/3/library/dataclasses.html#dataclasses.dataclass) ## Test Plan new mdtests --------- Co-authored-by: David Peter <mail@david-peter.de>
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1.3 KiB
replace
The replace function and the replace protocol were added in Python 3.13:
https://docs.python.org/3/whatsnew/3.13.html#copy
[environment]
python-version = "3.13"
Basic
from copy import replace
from datetime import time
t = time(12, 0, 0)
t = replace(t, minute=30)
reveal_type(t) # revealed: time
The __replace__ protocol
Dataclasses
Dataclasses support the __replace__ protocol:
from dataclasses import dataclass
from copy import replace
@dataclass
class Point:
x: int
y: int
reveal_type(Point.__replace__) # revealed: (self: Point, *, x: int = int, y: int = int) -> Point
The __replace__ method can either be called directly or through the replace function:
a = Point(1, 2)
b = a.__replace__(x=3, y=4)
reveal_type(b) # revealed: Point
b = replace(a, x=3, y=4)
reveal_type(b) # revealed: Point
A call to replace does not require all keyword arguments:
c = a.__replace__(y=4)
reveal_type(c) # revealed: Point
d = replace(a, y=4)
reveal_type(d) # revealed: Point
Invalid calls to __replace__ or replace will raise an error:
e = a.__replace__(x="wrong") # error: [invalid-argument-type]
# TODO: this should ideally also be emit an error
e = replace(a, x="wrong")