Swift泛型方法应该使用重载泛型函数(Swift generic method should use overloaded generic function)

 我无法使用Swift泛型获得所需的效果。 我定义了一些通用函数，但是对于特定情况，我想覆盖它们以提供其他功能。 当我从非泛型方法/函数调用函数时，一切正常（它在参数类型匹配时使用特定版本，否则使用泛型版本），但是当我从泛型方法/函数调用函数时，它总是使用泛型功能的版本（从不具体版本）。 
 
 这是一个示例游乐场： 
 
func printSomething <T> (something: T) {
    println("This is using the generic version.")
    println(something)
}

func printSomething(string: String) {
    println("This is using the specific version.")
    println(string)
}

func printSomeMoreThings <T> (something: T) {
    printSomething(something)
}

class TestClass <T> {

    var something: T

    init(something: T) {
        self.something = something
    }

    func printIt() {
        printSomething(self.something)
    }
}

printSomething("a")
println()
printSomeMoreThings("b")

let test = TestClass(something: "c")
println()
test.printIt()
 
 这给出了以下输出： 
 
This is using the specific version.
a

This is using the generic version.
b

This is using the generic version.
c
 
 我希望它一直使用特定的版本（因为它一直使用String参数调用printSomething）。 有没有办法在不使用特定String版本重载每个方法/函数的情况下执行此操作。 特别是对于Class的情况，因为我不能为特定类型的T重载类方法？ 

I'm having trouble getting the desired effect with Swift generics. I defined some generic functions, but for specific cases I would like to override them to provide additional features. When I call the functions from a non generic method/function everything works fine (it uses the specific versions when the argument types match and the generic version otherwise), but when I call the functions from a generic method/function it always uses the generic version of the function (never the specific versions).
 
Here's an example playground:
 
func printSomething <T> (something: T) {
    println("This is using the generic version.")
    println(something)
}

func printSomething(string: String) {
    println("This is using the specific version.")
    println(string)
}

func printSomeMoreThings <T> (something: T) {
    printSomething(something)
}

class TestClass <T> {

    var something: T

    init(something: T) {
        self.something = something
    }

    func printIt() {
        printSomething(self.something)
    }
}

printSomething("a")
println()
printSomeMoreThings("b")

let test = TestClass(something: "c")
println()
test.printIt()
 
This gives the following output:
 
This is using the specific version.
a

This is using the generic version.
b

This is using the generic version.
c
 
I would like it to use the specific version all the time (since it's calling printSomething with a String argument all the time). Is there a way to do this without overloading every method/function with a specific String version. Especially for the Class case, because I can't overload the class methods for specific types of T?

原文：https://stackoverflow.com/questions/29717698