如何停止与元组类型匹配的 Swift 中的通用 function ？

Question

I have these two methods

func doSomething<T>(_ completion: (T) -> Void) { ... }

func doSomething<T, U>(_ completion: (T, U) -> Void) { ... }

Unfortunately, this won't compile when I try to use the version with two generic types.

doSomething { (value1: String, value2: Int) in ... }

Because it's ambiguous between the second doSomething<String, Int> and the first doSomething<(String, Int)> ie a single generic type which is a tuple containing the two strings.

Obviously, I can call these methods two different names? Is there a way to resolve this ambiguity without doing that?

Answer 1

(  doSomething as ( (String, Int) -> Void ) -> Void  ) { value1, value2 in }

You could make a type alias…

typealias DoSomething<T, U> = ( (T, U) -> Void ) -> Void

(doSomething as DoSomething) { (value1: String, value2: Int) in }
(doSomething as DoSomething<String, Int>) { _ = ($0, $1) }

…but type aliases can't be overloaded, so you'd need one for every function overload but one. And there'd be no point in that; giving the functions different names would be simpler.