[swift-evolution] repeat loop enhancement

[Erica Sadun]

You can do:

(0 ..< count).forEach {
    // Do something here
}

You can also easily extend Int for a similar result:

public extension Int {
    func times(@noescape body: () -> Void) {(0..<self).forEach{_ in body()}}
}

-- E

> On Dec 8, 2015, at 2:54 PM, Jason Pollack via swift-evolution <swift-evolution at swift.org> wrote:
> 
> I'd like to propose a small enhancement to the repeat loop.
> 
> Currently if we want to perform 'count' iterations in a loop, we need to do something like:
> 
> for _ in 0 ..< count {
>    //Do something here
> }
> 
> It looks and feels a little awkward. We need to create an unnamed variable, and it's easy to forget (especially for language newcomers) that the loop starts with 0 and doesn't include count.
> 
> We can also do:
> 
> var i = 0
> repeat {
>     //Some code
>     i += 1
> } while i < 10
> 
> This is worse, in that it introduces a variable in the outer scope, and puts the repeat count at the end. Plus, if the expression inside the repeat is complex, the value of i may never be incremented, or may be incremented more than once.
> 
> 
> I propose the following:
> 
> repeat count {
>     //Do something here
> }
> 
> It's cleaner, and IMO clearer what this code is intended to do.
> 
> Naturally 'count' should be non-negative. A while clause is not needed, although I could imagine it being supplied, to create a construct such as:
> 
> var ok = true
> repeat numberOfTimes {
>     //Do something, possibly set ok to false
> } while ok
> 
> This would repeat the loop a maximum of  'numberOfTimes', but could be ended early if some signal 'ok' is set to false (or, of course, by a break statement).
> 
> Thoughts?
> 
> Thanks!
> -Jason-
>  _______________________________________________
> swift-evolution mailing list
> swift-evolution at swift.org
> https://lists.swift.org/mailman/listinfo/swift-evolution

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