Swift generics not preserving type

Question

I\'m trying cast and/or generate a variable based upon the specified generic type. I understand there is no type erasure in swift, but it doesn\'t seem like the generics pre

Answer 1

The problem is var instance = T() Initialisers are not virtual so the instance is always made with BaseClass()^*. The following code uses a class function to work around the problem:

class BaseClass {
    func printme() -> String {
        return "I am BaseClass"
    }
    class func makeInstance() -> BaseClass
    {
        return BaseClass()
    }
}

class DerivedClass : BaseClass {
    override class func makeInstance() -> BaseClass
    {
        return DerivedClass()
    }

    override func printme() -> String {
        return "I am DerivedClass"
    }
}

class Util {
    func doSomething() -> String {
        var instance = T.makeInstance()
        return instance.printme()
    }
}

var util = Util()
println("\(util.doSomething())")

I changed the implementation of printme() only because the original code didn't print anything in a playground for some reason.

^* I think this is still a bug.