Swift XXXLiteralConvertible 协议的使用

struct  Pos: IntegerLiteralConvertible {
    var x: Int = 0
    var y: Int = 0
    
    init(integerLiteral value: IntegerLiteralType) {
        x = value
        y = value
    }
}

let pos: Pos = 100 //正常情况下，是无法用＝号直接初始化结构体的，因为Pos继承了IntegerLiteralConvertible 协议（接口）所以没有问题。

println(pos.x)
println(pos.y)

/*
 同样的还有
BooleanLiteralConvertible
FloatLiteralConvertible
StringLiteralConvertible
ArrayLiteralConvertible
DictionaryLiteralConvertible
NilLiteralConvertible
*/

//再看一个Class的例子
class Person: StringLiteralConvertible {
    var name = ""
    
    
    init(name n:String){
        name = n
    }
    
    typealias ExtendedGraphemeClusterLiteralType = String
    typealias UnicodeScalarLiteralType = String
    
    required convenience init(stringLiteral value: StringLiteralType){
        self.init(name: value)
    }
    
    //实际上起作用的是上面的方法，但是因为 StringLiteralConvertible 同样继承自定义了下面两个方法的协议（代理），所以也要定义一次
    required convenience init(extendedGraphemeClusterLiteral value: ExtendedGraphemeClusterLiteralType){
        self.init(name: value)
    }
    
    required convenience init(unicodeScalarLiteral value: UnicodeScalarLiteralType){
        self.init(name: value)
    }
    
    func call() {
        println(name)
    }
}

var zhang: Person = "123123"
zhang.call() //123123