How can I make typeof(this) return the type of a calling derrived class from a function in a base class?

[Milan Suk via Digitalmars-d-learn]

On Friday, 16 June 2017 at 13:46:14 UTC, Lester wrote:
> If I have something like the following:
>
> class A {
>     void foo(){ writeln(typeof(this)); }
>     ...
> }
>
> class B : A {
>     ...
> }
>
> And I want the results:
>
> A a = new A;
> B b = new B;
> a.foo(); // prints "A"
> b.foo(); // prints "B"
>
> How would I go about doing that? At the moment b.foo() is 
> printing "A".

What about something like this?

  class A {}
  class B : A {}

  void foo(T)(T object) {
      import std.stdio : writeln;

      writeln(object.classinfo.toString); // you can use whatever 
property you want...
  }

  void main()
  {
      A a = new A;
      B b = new B;
      a.foo(); // prints "test.A"
      b.foo(); // prints "test.B"
  }