comparison mercurial/interfaces/modules.py @ 51934:09f3a6790e56

interfaces: add the optional `bdiff.xdiffblocks()` method PyCharm flagged where this was called on the protocol class in `mdiff.py` in the previous commit, but pytype completely missed it. PyCharm is correct here, but I'm committing this separately to highlight this potential problem- some of the implementations don't implement _all_ of the methods the others do, and there's not a great way to indicate on a protocol class that a method or attribute is optional- that's kinda the opposite of what static typing is about. Making the method an `Optional[Callable]` attribute works here, and keeps both PyCharm and pytype happy, and the generated `mdiff.pyi` and `modules.pyi` look reasonable. We might be getting a little lucky, because the method isn't invoked directly- it is returned from another method that selects which block function to use. Except since it is declared on the protocol class, every module needs this attribute (in theory, but in practice this doesn't seem to be checked), so the check for it on the module has to change from `hasattr()` to `getattr(..., None)`. We defer defining the optional attrs to the type checking phase as an extra precaution- that way it isn't an attr with a `None` value at runtime if someone is still using `hasattr()`. As to why pytype missed this, I have no clue. The generated `mdiff.pyi` even has the global variable typed as `bdiff: intmod.BDiff`, so uses of it really should comply with what is on the class, protocol class or not.
author Matt Harbison <matt_harbison@yahoo.com>
date Sun, 29 Sep 2024 02:03:20 -0400
parents f2832de2a46c
children fa7059f031a9
comparison
equal deleted inserted replaced
51933:f2832de2a46c 51934:09f3a6790e56
6 from __future__ import annotations 6 from __future__ import annotations
7 7
8 import typing 8 import typing
9 9
10 from typing import ( 10 from typing import (
11 Callable,
11 List, 12 List,
13 Optional,
12 Protocol, 14 Protocol,
13 Tuple, 15 Tuple,
14 ) 16 )
15 17
16 if typing.TYPE_CHECKING: 18 if typing.TYPE_CHECKING:
17 BDiffBlock = Tuple[int, int, int, int] 19 BDiffBlock = Tuple[int, int, int, int]
18 """An entry in the list returned by bdiff.blocks().""" 20 """An entry in the list returned by bdiff.{xdiff,}blocks()."""
21
22 BDiffBlocksFnc = Callable[[bytes, bytes], List[BDiffBlock]]
23 """The signature of `bdiff.blocks()` and `bdiff.xdiffblocks()`."""
19 24
20 25
21 class BDiff(Protocol): 26 class BDiff(Protocol):
22 """A Protocol class for the various bdiff module implementations.""" 27 """A Protocol class for the various bdiff module implementations."""
23 28
30 def blocks(self, a: bytes, b: bytes) -> List[BDiffBlock]: 35 def blocks(self, a: bytes, b: bytes) -> List[BDiffBlock]:
31 ... 36 ...
32 37
33 def fixws(self, text: bytes, allws: bool) -> bytes: 38 def fixws(self, text: bytes, allws: bool) -> bytes:
34 ... 39 ...
40
41 xdiffblocks: Optional[BDiffBlocksFnc]
42 """This method is currently only available in the ``cext`` module."""