[swift-evolution] [Idea] Expression to retrieve the Objective-C selector of a method

[Félix Cloutier]

I really only was talking about the case where the compiler knows that it's an @objc method (with the understanding that the information is lost as soon as you make an unattributed T -> U closure out of it).

Either syntax would make me happy.

Félix

> Le 28 déc. 2015 à 13:49:22, Joe Groff <jgroff at apple.com> a écrit :
> 
>> 
>> On Dec 28, 2015, at 10:46 AM, Félix Cloutier <felixcca at yahoo.ca <mailto:felixcca at yahoo.ca>> wrote:
>> 
>> Would it be possible to add properties to closures/method objects?
>> 
>> Right now, it's possible to write:
>> 
>>> @objc
>>> class Foo : NSObject {
>>> 	func doSomething(value: Int) -> Int {
>>> 		return value + 1
>>> 	}
>>> }
>>> 
>>> let method = Foo.doSomething
>> 
>> Maybe we could have Foo.doSomething.selector for @objc methods?
> 
> Once you have a normal function value, it's not guaranteed you can recover any identity from it, since an arbitrary T -> U doesn't necessarily correspond to an @objc method. I'm proposing we do this by type context, similar to how we form C function pointers and blocks. Just like you can do:
> 
> let fptr: @convention(c) (Double) -> Double = sqrt
> 
> to get the function pointer for `sqrt`, you could say:
> 
> let sel: Selector = Foo.doSomething
> 
> to get the selector for `doSomething`.
> 
> -Joe

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