[swift-evolution] Name disambiguation of computed property/function with same type defined in extensions

[Paul Cantrell]

> On Jun 7, 2016, at 11:36 AM, Paul Cantrell via swift-evolution <swift-evolution at swift.org> wrote:
> 
>> 
>> On Jun 7, 2016, at 10:47 AM, L. Mihalkovic via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> wrote:
>> 
>> On Jun 7, 2016, at 4:53 PM, Tony Allevato <allevato at google.com <mailto:allevato at google.com>> wrote:
>> 
>>> I like the "from" keyword the best, but I'll take my own stab at a modification:
>>> 
>>>     import ModuleA
>>>     import ModuleB
>>> 
>>>     "hello world".(capitalized from ModuleA)()
>>>     "hello world".(capitalized from ModuleB)()
>>>     "hello world".(someProperty from ModuleA)
>>>     "hello world".(someProperty from ModuleB)
>> 
>> Hmmm... looks like an oxymoron in its own right... I was under the impression so far that the point of extensions was that they are not tied to a source. This brings us back full circle to the very definition of extensions... However you slice it, swift is lacking some scoping bellow modules, and/or arround some of the language features.
> 
> IIRC, a member of the core team (Joe Groff, maybe?) indicated several months ago on the list that methods are internally namespaced to their module. Alas, I can’t find that message. It was a long time ago.

Ah, here it is: https://lists.swift.org/pipermail/swift-evolution/Week-of-Mon-20151207/000928.html

Joe Groff wrote:

“It's helpful to think of method names as being namespaced in Swift, by both their enclosing module and type. If two modules independently extend a protocol with a method of the same name, you still semantically have two distinct methods that dispatch independently. The extension would have to be factored into a common module both modules see for them to interact.”

IOW, yes, Swift internally does something very much like "hello world”.ModuleA::capitalized().

> You can see this in the fact that two different files can see two different extension methods:
> 
> A.swift
> 
>     import ModuleA
>     …
>     "hello world".capitalized()
> 
> B.swift
> 
>     import ModuleB
>     …
>     "hello world".capitalized()
> 
> …even if they end up compiled into the same binary. And that makes sense: A.swift only expected to see ModuleA’s extension, and was presumably coded around that expectation. That ModuleB happened to end up mixed into the same binary shouldn’t change the behavior of A.swift
> 
> If my understand is correct, then my "hello world”.ModuleA::capitalized() and your "hello world".(capitalized from ModuleA)() are both just syntax to expose something that Swift already tracks internally.
> 
> Cheers, P
> 
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