8
考虑下面的游乐场:斯威夫特协议继承和泛型函数
import Foundation
protocol StringInitable {
init(string:String)
}
class A : StringInitable {
var stored:String
required init (string:String) {
stored = string
}
}
class B : A /*, StringInitable */ {
var another_stored:String
required init (string:String) {
another_stored = "B-store"
super.init(string: string)
}
}
func maker<T:StringInitable>(string:String) -> T {
return T(string: string)
}
let instanceA = A(string: "test-maker-A")
let instanceB = B(string: "test-maker-B")
let makerA:A = maker("test-maker-A")
let makerB:B = maker("test-maker-B")
let typeInstanceA = _stdlib_getTypeName(instanceA)
let typeMakerA = _stdlib_getTypeName(makerA)
let typeInstanceB = _stdlib_getTypeName(instanceB)
let typeMakerB = _stdlib_getTypeName(makerB)
从编译器似乎已经推断出正确的类型,但未能调用正确的初始化结果。为什么我必须在B类中显式实现StringInitable(通过删除B类定义中的注释来测试)才能让泛型函数“maker”调用正确的初始化方法?
它为我的初始化一旦我在初始化函数前面加了“需要”符。 – user965972 2015-06-06 19:45:01