Add a wrapper around std::visit that accepts multiple overloads#10771
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jschmidt-icinga wants to merge 3 commits into
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Add a wrapper around std::visit that accepts multiple overloads#10771jschmidt-icinga wants to merge 3 commits into
std::visit that accepts multiple overloads#10771jschmidt-icinga wants to merge 3 commits into
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Al2Klimov
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julianbrost
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A quick test case demonstrating that this works as expected would be pretty nice. Doesn't need to be super fancy, something like running [](auto x) { return x.size(); } on two instances of variant<string, vector>, and something similar for the case where multiple overloads are passed to Visit().
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Done. Added a section about the tests to the PR description. Note: I still think it's worth having these tests; Assumptions should be verified, compiler bugs exists etc.
This allows to dispatch multiple overloads that do different things based on the underlying type and also nicer formatting with clang-format in case there is only one overload, because the lambda is the second/last parameter.
This is just to show how icinga::Visit improves readability and makes some (not all) if constexpr statements inside std::visit unnecessary.
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This adds a wrapper around
std::visitthat accepts only a single variant, but multiple overload alternatives that cover all the types in the variant. As an added benefit, having the function object as the last parameter will lead to nicer formatting fromclang-format, in case only one generic overload is provided, with only a single level of indentation.In addition, to showcase the function, this PR refactors
PerfdataWriterConnectionto use it to dispatch on itsm_Streamvariant.Testing
I've added two test-cases that showcase operation of
Visitboth with a singleauto&typed lambda and multiple for explicit type pattern matching.Strictly speaking, these tests aren't really necessary, since the compiler ensures that:
doublein the variant, overloads forintandfloat)Since the function is not picked by dark template-meta-programming magic that might force conversions or pick the wrong overload by chance, but with standard overload resolution, that should always be fine. Or at least I can't come up with a situation where this wouldn't lead to a compiler error but something unexpected off the top of my head.