`Generic` Protocols

generic-protocols.swift

class Container<T> {
    private var containedValue: T
    
    init(_ value: T) {
        containedValue = value
    }
}

protocol ContainerProtocol {
    typealias ValueType
    var value: ValueType { get set }
}

extension Container: ContainerProtocol {
    typealias ValueType = T
    var value: ValueType {
        get {
            return self.containedValue
        }
        set {
            self.containedValue = newValue
        }
    }
}

class App<T: ContainerProtocol where T.ValueType == Int> {
    var container: T
    
    init(_ container: T) {
        self.container = container
    }
}

App(Container(5))