[swift-users] Conditional generic initializers?

[Karl]

Yes. You need to put it in an extension.

extension Foo where T1 == T2 {
    convenience init(values: [T1]){
    ….
    }
}

> On 15 May 2016, at 14:45, Neil Faiman via swift-users <swift-users at swift.org> wrote:
> 
> Is it possible for a generic class to have methods (specifically, initializers) which are only defined if the generic parameters meet certain constratins?
> 
> Here’s a concrete example:
> 
>    class Foo <T1, T2> {
>        init(pairs: [(T1, T2)]) {}
>        // What I’d like to be able to doL
>        convenience init "where T1 == T2" (values: [T1]) { self.init(pairs: values.map{ ($0, $0) }) }
>    }
> 
> That is, I’d like to provide a convenience initializer that takes an array of values instead of pairs, and turns the values into pairs, IF THE TWO GENERIC TYPE PARAMETERS ARE THE SAME.
> 
> I can’t find a way to accomplish this. Is there one?
> 
> Thanks,
> 
> 	Neil Faiman
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