What is the right way to store in a structure a class (not an instance) derived from a given interface(s)?

On Tuesday, 19 February 2019 at 22:04:58 UTC, Victor Porton wrote:
> What is the right way to store in a structure a class (not an instance) derived from a given interface(s)?

What are you trying to do with the "class"? If you just want a static "reference" to it you can use an `alias`:

  class A {}
  struct B {
    alias C = A;
  }
  new B.C();

If you want dynamic information on the type you can use TypeInfo:

  class A {}
  struct B {
    TypeInfo i;
  }
  B b;
  b.i = typeid(A);
  b.i.factory();

Or more simply if you just want to construct instances, just use a delegate:

  interface I {}
  class A : I {}
  struct B {
    I delegate() factory;
  }
  B b;
  b.factory = () => new A();
  b.factory();

You *can't* do something like the following because types need to be validated at compile time:

  struct A {
    Class cls;
  }
  A a;
  a.cls b;
  b.run();