PaulHudson_ProtocolOrientedProgramming

protocol Payable {
    func calculateWages() -> Int
}

extension Payable {
    func calculateWages() -> Int {
        return 10000
    }
}

protocol ProvidesTreatment {
    func treat(name: String)
}

extension ProvidesTreatment {
    func treat(name: String) {
        print("I have treated \(name)")
    }
}

protocol ProvidesDiagnosis {
    func diagnose() -> String
}

extension ProvidesDiagnosis {
    func diagnose() -> String {
        return "He's dead, Jim"
    }
}

protocol ConductSurgery {
    func performSurgery()
}

extension ConductSurgery {
    func performSurgery() {
        print("Success!")
    }
}

protocol HasRestTime {
    func takeBreak()
}

extension HasRestTime {
    func takeBreak() {
        print("Time to watch TV")
    }
}

protocol NeedsTraining {
    func study()
}

extension NeedsTraining {
    func study() {
        print("I'm reading a book")
    }
}

protocol Employee: Payable, HasRestTime, NeedsTraining { }

struct Receptionist { }
struct Nurse { }
struct Doctor { }
struct Surgeon { }

extension Receptionist: Employee { }
extension Nurse: Employee, ProvidesTreatment { }
extension Doctor: Employee, ProvidesTreatment, ProvidesDiagnosis { }
extension Surgeon: Employee, ProvidesDiagnosis, ConductSurgery { }

extension Employee where Self: ProvidesTreatment {
    func checkInsurance() {
        print("Yup, I'm totally insured")
    }
}

extension Collection where Iterator.Element: BinaryInteger {
    func countOddEven() -> (odd: Int, even: Int) {
        
        var even = 0
        var odd = 0
        
        for val in self {
            if val % 2 == 0 {
                even += 1
            } else {
                odd += 1
            }
        }
        
        return (odd, even)
    }
}