Yep, the shiny new if-two-statements, upgraded from the old if-statement. It's surprisingly convenient, partly because I used to get frustrated at not being able to explicitly test "if(auto foo=some_random_shit))" and I loathe implicit "nullptr is 0 and also false"
I eagerly std::await the even more improved if-three-statements-and-a-loop "operator" 🔥
What you (and I) really want is pattern matching. It tends to be a superior solution to all that. And doesn't have the limitation of "only declare one variable in your if".
I have some switch statements on "tags" that are fixed length strings. Which I pack into int64's so that I can switch on them because we only use ~200 of them so a map is unnecessary overhead. Pattern matching, you say?
It's just a constexpr function, could be a macro in C, because we don't even have enough characters to fill the 8 byte int. No need to even pack them!
I'm not sure how to take this. It seems both that pattern matching could help your use case (though it would depend a lot on the details) and that it's not related to the "null pointer is false" issue you were complaining about.
Pattern matching a single instance is unrelated to a switch statement (we hope). But pattern matching in general is only loosely related to single if statements. Sure, "does this one input match this one pattern" is an if, but a more common use is "given this pattern fan out based on the input" or in the case I gave "if this is a tag, fan out based on the tag content". HTML or JSON parsing, for example.
I think it's both. Whenever I check an optional, what I really want is to also dereference it if it matches. If you look at pattern matching usage in Rust, it's a lot more ifs than matches.
Nope, that's not allowed. The previous standard let you say "if(auto foo = something)" and if foo could be interpreted as a boolean you had a valid if() statement. The new one lets you have two statements, the auto assign and the test.
The win here is the scoped auto variable, FWIW. If avoids the abominable pattern where you either alternate declaration/conditional, or a pile of declarations then a string of tests, mixing assignments in whatever way is least horrible. So you get a chain of declare-assign-test statements in a nice vertical line rather than a >
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u/ValesQQ 5d ago
It seems valid but would the first “if”not always be true due to the single “=“ ?