Extending a struct which is inside another struct

Question

I'm trying to extend a struct that is already inside a struct. When I write the following code, I get

declaration is only valid at file scope.

struct A {
    struct AA {

    }
}

extension A {
    extension AA {

    }
}

Is it invalid to write an extension inside an extension?

[The relevant portion of the language guide](https://developer.apple.com/library/content/documentation/Swift/Conceptual/Swift_Programming_Language/Declarations.html#//apple_ref/doc/uid/TP40014097-CH34-ID378): *"Extension declarations can’t contain deinitializer or protocol declarations, stored properties, property observers, **or other extension declarations.***" — Hamish, Jan 10 '17 at 10:39
@Raphael Given the only explicit question OP asked was "*Is it invalid to write an extension inside an extension?*" – I'd say it's pretty relevant. — Hamish, Jan 10 '17 at 12:29
@Hamish Right, the titular "question" and the one in the body have different answers. I missed that last line since it was pretty clear from the rest of the body what they wanted (which is not to discuss language specification but extend `AA`), my bad. — Raphael, Jan 10 '17 at 12:31

score 7 · Accepted Answer · answered Jan 10 '17 at 10:35

7

It seems like the only way to do that is:

extension A.AA
{
   func test()
   {
      print("Test")
   }
}

It just worked in my playground

answered Jan 10 '17 at 10:35

Andrey Chernukha

1 Answers1