Unfortunately we don’t have a way to invoke a function with a runtime argument
list because that would require runtime code generation in the most general
case.
I would hack around it by handling the common cases of no arguments, 1
argument, 2 arguments, etc up to some fixed number of arguments that you
consider “enough”. Use a switch on the type of the function.
Slava
> On Nov 3, 2017, at 2:21 PM, C. Keith Ray via swift-users
> <swift-users@swift.org> wrote:
>
> In the code below, I'm trying to store a reference to a function with any
> number of arguments, with any return type. And I want to be able to invoke
> it.
>
> Help?
>
> See the comments with "*******"
>
> typealias Void = ()
>
> func equalTypes(_ me: [Any.Type], _ other: [Any.Type]) -> Bool {
> guard me.count == other.count else { return false }
>
> for i in 0 ..< me.count {
> if me[i] != other[i] { return false }
> }
> return true
> }
>
> struct Function {
> var returnType: Any.Type
> var argTypes: [Any.Type]
> var function: Any // ******* any function *******
>
> func perform(_ args: [Any]) -> Any {
> // ******* call function() with args, return result *******
> return 0
> }
>
> func isCompatible(_ other: Function) -> Bool {
> return self.returnType == other.returnType &&
> equalTypes(argTypes, other.argTypes)
> }
> }
>
> func vToV() {
> print("vToV")
> }
>
> func intToInt(_ i: Int) -> Int {
> print("intToInt")
> return 4
> }
>
> let f = Function(returnType: Void.self,
> argTypes: [],
> function: vToV)
> let r = f.perform([])
> print(r)
>
> let f2 = Function(returnType: Int.self,
> argTypes: [Int.self],
> function: intToInt)
> let r2 = f2.perform([12])
> print(r2)
>
> assert(f.isCompatible(f))
> assert(!f.isCompatible(f2))
>
>
> --
> C. Keith Ray
> Senior Software Engineer / Trainer / Agile Coach
> * http://www.thirdfoundationsw.com/keith_ray_resume_2014_long.pdf
> <http://www.thirdfoundationsw.com/keith_ray_resume_2014_long.pdf>
>
>
>
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> swift-users@swift.org
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