Type safe option value getter #14561
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bruchar1
suggested changes
May 6, 2025
Yeah, I didn't plan to merge them that way, just have smaller chunks to review |
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bruchar1
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May 7, 2025
This provides a variant of `get_value_for` that does run-time type checking, but in a way that allows static type checkers like mypy to understand. This gives us the two fold advantage of runtime checking of types that can't be statically known and not having to write a lot `assert isinstance(...), 'for mypy'` checks.
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It belongs here, rather than in the CoreData.
Be more consistent
We have a fallback parameter now, so we can avoid the exception handling by providing a sane or sentinel default value instead
This pattern repeats a lot in the Compiler, and the compiler even has it's own implementation of this (which will be removed shortly).
This was an unsafe version of the other function, but without proper subproject handling. In most cases (except unittests) the safe variant was actually better anyway, especially with the fallback parameter
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dnicolodi
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May 17, 2025
| @@ -889,7 +890,19 @@ def get_value_object_and_value_for(self, key: OptionKey) -> T.Tuple[AnyOptionTyp | |||
| computed_value = vobject.validate_value(self.augments[key]) | |||
| return (vobject, computed_value) | |||
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| def get_value_for(self, name: 'T.Union[OptionKey, str]', subproject: T.Optional[str] = None) -> ElementaryOptionValues: | |||
| def get_value_for(self, key: OptionKey, type_: T.Type[ElementaryOptionTypes], | |||
| *, fallback: T.Optional[ElementaryOptionTypes] = None) -> ElementaryOptionTypes: | |||
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Maybe default would be more in line to how the same concept is named in the Pyrthon APIs than fallback
dnicolodi
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May 17, 2025
mesonbuild/options.py
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| @@ -1161,7 +1161,7 @@ def get_default_for_b_option(self, key: OptionKey) -> ElementaryOptionValues: | |||
| assert self.is_base_option(key) | |||
| try: | |||
| return T.cast('ElementaryOptionValues', COMPILER_BASE_OPTIONS[key.evolve(subproject=None)].default) | |||
| except KeyError: | |||
| except KeyErrorexcept Key: | |||
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This (ultimately) makes the
OptionStore.get_option_value()type safe, but using a generic with a bound type. This allows us to both have runtime type checking, and allows mypy (and other type checkers) to see that at static inspection time and treat the return as safe. This, in turn, allows us to remove a lot ofassert isinstance(...), 'for mypy'checks, with a properMesonBugExceptionwith a more helpful error message.The addition of a fallback parameter also allows us to remove a bunch of
if key in options and options.get_value_for(key)style checks, through the use of the fallback.This series has been split into a bunch of patches to attempt to make review easier, but I'm perfectly happy to squash any number of them into less patches before merging.