swifttuplesswift-extensionsswift-protocols

Can I extend Tuples in Swift?

I'd like to write an extension for tuples of (e.g.) two value in Swift. For instance, I'd like to write this swap method:

let t = (1, "one")
let s = t.swap

such that s would be of type (String, Int) with value ("one", 1). (I know I can very easily implement a swap(t) function instead, but that's not what I'm interested in.)

Can I do this? I cannot seem to write the proper type name in the extension declaration.

Additionally, and I suppose the answer is the same, can I make a 2-tuple adopt a given protocol?

Solution

  • You cannot extend tuple types in Swift. According to Types, there are named types (which can be extended) and compound types. Tuples and functions are compound types.

    See also (emphasis added):

    Extensions
    Extensions add new functionality to an existing class, structure, or enumeration type.