check dispatching.swift

#!/usr/bin/env swift
import Foundation

protocol TestProtocol {
	func foo(_ param: Int)
}

extension TestProtocol {
	func foo() {
		print("Default implementation")
		foo(0) 
	}
}


class API: TestProtocol {
	private var _implementation: TestProtocol = MyApiUnderlineImplementation()

	func foo(_ param: Int) {
		_implementation.foo()
	}
}

class MyApiUnderlineImplementation: TestProtocol {
	func foo(_ param: Int) {
		foo()
	}

	func foo() {
		print("MyApiUnderlineImplementation")
	}
}

let api = API()
api.foo()