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## Summary We're actually quite good at computing this but the main issue is just that we compute it at the type-level and so wrap it in `Literal[...]`. So just special-case the rendering of these to omit `Literal[...]` and fallback to `...` in cases where the thing we'll show is probably useless (i.e. `x: str = str`). Fixes https://github.com/astral-sh/ty/issues/1882
1.5 KiB
1.5 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)
# TODO: this should be `time`, once we support specialization of generic protocols
reveal_type(t) # revealed: Unknown
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 = ..., y: 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)
# TODO: this should be `Point`, once we support specialization of generic protocols
reveal_type(b) # revealed: Unknown
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)
# TODO: this should be `Point`, once we support specialization of generic protocols
reveal_type(d) # revealed: Unknown
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")