CODEWITHSUNDEEP
swift
Michael Bernat
Michael Bernat

Reputation: 646

How works "guard case let" for non-enums

Please, can anyone explain why this works?

func howMany() -> Int {return 11}
guard case let output = howMany(), output > 10 else {return}

I understand how guard/if/while/for case let works with enums. Pattern matching is great. But here is no enum and this works too. What is the language construct that allows that?

(This example was taken from Matt Neuburg's book.)

Upvotes: 4

Views: 1263

Answers (1)

matt
matt

Reputation: 534977

It's the if case construct. (guard is merely a negative if, if you see what I mean.)

The whole idea of this construct is that it lets you use an ordinary if or guard while taking advantage of switch case pattern matching. A major use is to do extraction of an associated value from an enum without the heavyweight switch construct, but you can use it anywhere that pattern matching in a condition makes sense (as here).

See also https://stackoverflow.com/a/37888514/341994

Upvotes: 3

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