I have:

class OperatorV(T) : Value {
 T impl;

 this(T impl) {
   this.impl = impl;
 }
...

and use it like this: makeOperator((IntV a, IntV b) => new IntV(a.num + b.num));

Now I want to do: opWord.get() returns a Value

OperatorV *op = cast(OperatorV*)(opWord.get());

and get: Error: class app.OperatorV(T) is used as a type

Hmm... any idea? Don't know how to carry the template stuff around.

-- 
Robert M. Münch
http://www.saphirion.com
smarter | better | faster

On Sun, 31 Jan 2016 19:59:01 +0100, Robert M. Münch wrote:

> I have:
> 
> class OperatorV(T) : Value {
>   T impl;
> 
>   this(T impl) {
>     this.impl = impl;
>   }
> ...

This expands to:

template OperatorV(T) {
  class OperatorV {
    ...
  }
}

If you're just typing `OperatorV` with no template arguments, you're referring to the template itself.

There's not necessarily any relationship between two instantiations of a template with different arguments. You could write it so that OperatorV! int and OperatorV!string have entirely different sets of methods, constructors, and fields.

Because of that, the compiler doesn't create a base class for you automatically. But you can do it yourself:

class BaseOperator {}  // or interface, or abstract class
class OperatorV(T) : BaseOperator {}