class RentalCar {
private var nameBV:String;
private var passengersBV:Int;
private var priceBV:Float;
private init(name:String,passengers:Int,price:Float) {
self.nameBV = name;
self.passengersBV = passengers;
self.priceBV = price;
}
final var name:String { get { return nameBV; }}
final var passengers:Int { get { return passengersBV; }};
final var pricePerDay:Float { get { return priceBV; }};
class func createRentalCar(passengers:Int) -> RentalCar? {
var carImpl:RentalCar.Type?;
switch (passengers) {
case 0...3:
carImpl = Compact.self;
case 4...8:
carImpl = SUV.self
default:
carImpl = nil;
}
return carImpl?.createRentalCar(passengers);
}
}
class Compact : RentalCar {
private convenience init() {
self.init(name: "VW Golf",passengers: 3,price: 20);
}
private override init(name: String,passengers: Int,price: Float) {
super.init(name: name,passengers: passengers,price: price);
}
override class func createRentalCar(passengers:Int) -> RentalCar? {
if (passengers < 2) {
return sharedInstance;
} else {
return SmallCompact.sharedInstance;
}
}
class var sharedInstance:RentalCar {
get {
struct SingletonWrapper {
static let singleton = Compact();
}
return SingletonWrapper.singleton;
}
}
}
class SmallCompact : Compact {
private init() {
super.init(name: "Ford Fiesta",price: 15);
}
override class var sharedInstance:RentalCar {
get {
struct SingletonWrapper {
static let singleton = SmallCompact();
}
return SingletonWrapper.singleton;
}
}
}
class SUV : RentalCar {
private init() {
super.init(name: "Cadillac Escalade",passengers: 8,price: 75);
}
override class func createRentalCar(passengers:Int) -> RentalCar? {
return SUV();
}
}
原文地址：https://www.jb51.cc/swift/326332.html
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