Swift's Polymorphism Test

gistfile1.swift

protocol O {
	func f() -> String
}

struct A : O {
	func f() -> String {
		return "a"
	}
}

class B : O {
	func f() -> String {
		return "b"
	}
}

//////////////////////////////////////

let a = A()
let b = B()
var o : O

NSLog("%@", a.f()) // a
NSLog("%@", b.f()) // b

o = a
NSLog("%@", o.f()) // a

o = b
NSLog("%@", o.f()) // b