Korne127 comments on Slapping on a `.expect` is also error handling!

[–] Korne127@lemmy.world 15 points 1 year ago (5 children)

I mean using unwrap is not bad practice if the value is guaranteed to not be none, which can happen frequently in some applications.

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[–] qaz@lemmy.world [S] 9 points 1 year ago* (last edited 1 year ago)

A good example would be regex. After validating it when writing the program it should always compile, although this could also be solved with a proc macro that validates the regex at compile time.

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[–] mobotsar@sh.itjust.works 4 points 1 year ago* (3 children)

If it's guaranteed to not be None, why is it an Option?

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[–] emilgardis@lemmy.ml 2 points 1 year ago

Here's a bad example but hopefully captures the why. https://play.rust-lang.org/?version=stable&mode=debug&edition=2024&gist=43d055381e7bb52569c339d4526818f4

We have a condition we know must be satisfied (the option will always be Some), but cant prove in code.

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[–] marcos@lemmy.world 2 points 1 year ago*

Oh, it can happen when you do calculations with compile-time constants...

But the GP's claim that it's a "frequent" thing is suspect.

(Crashing is also useful when you are writing and-user applications, but you'll probably want .expect like in the meme.)

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[–] Korne127@lemmy.world 1 point 1 year ago

A very typical use-case would be getting something from a HashMap (or a Vector) and calling unwrap because you know it must exist (as you got a reference to the index or object that must be valid in the HashMap or Vector).
Or if you call a function that returns Option<…> depending on the current state and you know that it must return Some(…) in the current situation.

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