Re: Implementing interfaces using alias this

[Steven Schveighoffer via Digitalmars-d-learn]

On 6/14/17 5:34 AM, Balagopal Komarath wrote:
Why doesn't this work? The Test!Duck type has a void quack() method but
the compiler says it is not implemented.
import std.stdio;

interface IDuck
{
    void quack();
}

class Test(T) : IDuck
{
    T data;
    alias data this;
}

struct Duck
{
    void quack()
    {
        writeln("Quack");
    }
}


void main()
{
    Test!Duck d;
}

An alias never causes implementation to be emitted. It should just be a 
forward from one symbol name to another. You need an actual function 
that can go into the vtable that takes a 'Test!Duck' as the context 
pointer. This wrapper has to be written by you.

-Steve