David Peter 0092794302 [ty] Use typing.Self for the first parameter of instance methods (#20517) ... ## Summary Modify the (external) signature of instance methods such that the first parameter uses `Self` unless it is explicitly annotated. This allows us to correctly type-check more code, and allows us to infer correct return types for many functions that return `Self`. For example: ```py from pathlib import Path from datetime import datetime, timedelta reveal_type(Path(".config") / ".ty") # now Path, previously Unknown def _(dt: datetime, delta: timedelta): reveal_type(dt - delta) # now datetime, previously Unknown ``` part of https://github.com/astral-sh/ty/issues/159 ## Performance I ran benchmarks locally on `attrs`, `freqtrade` and `colour`, the projects with the largest regressions on CodSpeed. I see much smaller effects locally, but can definitely reproduce the regression on `attrs`. From looking at the profiling results (on Codspeed), it seems that we simply do more type inference work, which seems plausible, given that we now understand much more return types (of many stdlib functions). In particular, whenever a function uses an implicit `self` and returns `Self` (without mentioning `Self` anywhere else in its signature), we will now infer the correct type, whereas we would previously return `Unknown`. This also means that we need to invoke the generics solver in more cases. Comparing half a million lines of log output on attrs, I can see that we do 5% more "work" (number of lines in the log), and have a lot more `apply_specialization` events (7108 vs 4304). On freqtrade, I see similar numbers for `apply_specialization` (11360 vs 5138 calls). Given these results, I'm not sure if it's generally worth doing more performance work, especially since none of the code modifications themselves seem to be likely candidates for regressions. | Command | Mean [ms] | Min [ms] | Max [ms] | Relative | |:---|---:|---:|---:|---:| | `./ty_main check /home/shark/ecosystem/attrs` | 92.6 ± 3.6 | 85.9 | 102.6 | 1.00 | | `./ty_self check /home/shark/ecosystem/attrs` | 101.7 ± 3.5 | 96.9 | 113.8 | 1.10 ± 0.06 | | Command | Mean [ms] | Min [ms] | Max [ms] | Relative | |:---|---:|---:|---:|---:| | `./ty_main check /home/shark/ecosystem/freqtrade` | 599.0 ± 20.2 | 568.2 | 627.5 | 1.00 | | `./ty_self check /home/shark/ecosystem/freqtrade` | 607.9 ± 11.5 | 594.9 | 626.4 | 1.01 ± 0.04 | | Command | Mean [ms] | Min [ms] | Max [ms] | Relative | |:---|---:|---:|---:|---:| | `./ty_main check /home/shark/ecosystem/colour` | 423.9 ± 17.9 | 394.6 | 447.4 | 1.00 | | `./ty_self check /home/shark/ecosystem/colour` | 426.9 ± 24.9 | 373.8 | 456.6 | 1.01 ± 0.07 | ## Test Plan New Markdown tests ## Ecosystem report * apprise: ~300 new diagnostics related to problematic stubs in apprise 😩 * attrs: a new true positive, since [this function](4e2c89c823/tests/test_make.py (L2135)) is missing a `@staticmethod`? * Some legitimate true positives * sympy: lots of new `invalid-operator` false positives in [matrix multiplication](cf9f4b6805/sympy/matrices/matrixbase.py (L3267-L3269)) due to our limited understanding of [generic `Callable[[Callable[[T1, T2], T3]], Callable[[T1, T2], T3]]` "identity" types](cf9f4b6805/sympy/core/decorators.py (L83-L84)) of decorators. This is not related to type-of-self. ## Typing conformance results The changes are all correct, except for ```diff +generics_self_usage.py:50:5: error[invalid-assignment] Object of type `def foo(self) -> int` is not assignable to `(typing.Self, /) -> int` ``` which is related to an assignability problem involving type variables on both sides: ```py class CallableAttribute: def foo(self) -> int: return 0 bar: Callable[[Self], int] = foo # <- we currently error on this assignment ``` --------- Co-authored-by: Shaygan Hooshyari <sh.hooshyari@gmail.com>		2025-09-29 21:08:08 +02:00
..
src	[ty] Use typing.Self for the first parameter of instance methods (#20517)	2025-09-29 21:08:08 +02:00
ast.toml	Implement template strings (#17851)	2025-05-30 15:00:56 -05:00
Cargo.toml	Make dependency get-size2 truly optional in ruff_python_ast (#19052)	2025-06-30 21:50:59 -05:00
generate.py	[ty] Add environment variable to dump Salsa memory usage stats (#18928)	2025-06-26 21:27:51 +00:00