[swift-evolution] array splatting for variadic parameters

Tino Heth 2th at gmx.de
Sat Feb 11 06:08:02 CST 2017

> func f(_ args: [Int]) {
>   // Some implementation ...
> }
> func f(_ args: Int…) {
>   f(args)
> }
> Some people also advocate (myself generally included) that one should prefer the signature explicitly marking args as an array, as the syntactic overhead of wrapping the arguments with “[]” when calling f is arguably bearable. However, in some other situations, this approach might not be applicable. For instance, one may simply not be able to modify the original function. Another use-case may be a function that should forward its own variadic parameters.

There has been a proposal that would not only solve this issue, but also add a lot flexibility while simplifying the language at the same time:
https://github.com/Haravikk/swift-evolution/blob/a13dc03d6a8c76b25a30710d70cbadc1eb31b3cd/proposals/nnnn-variadics-as-attribute.md <https://github.com/Haravikk/swift-evolution/blob/a13dc03d6a8c76b25a30710d70cbadc1eb31b3cd/proposals/nnnn-variadics-as-attribute.md>

Imho it's one of the best ideas I have seen on evolution, and definitely the most valuable segregation of C legacy.
Sadly, it was discussed in a very busy timeframe, and I think it really didn't receive the attention it deserves…

I would have asked Haravikk wether he would like to start a second try anyways, and as this topic is directly related, it's a good motivation to do so.

The basic idea of the proposal is to get rid of "…"-magic and declare variadic parameters with their natural type (Array<T> — but one aspect of this idea is that it can be extended easily to work with sets and other types that can be expressed with an array literal).
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