[swift-evolution] Compiler directive for current closure reference

[Taras Zakharko]

Dear all, 

I apologise in advance if this has already been suggested (or maybe even implemented), but its very difficult to keep track of the swift evolution list :) 

We already have compiler directives like #line, #function. I would like to suggest a new directive #closure (name preliminary) that expands to the reference to the closure, function or method in whose body the directive occurs. Motivation: this will allow one to conveniently use design patterns like these:

addHandler({
	guard stillRelevant() else {
          removeHandler(#closure)
	}
      
       doSomething()
})


I am sure there are also other cases where such directive would come in handy.