• Gheorghe Gabriel (14/14) Nov 26 2018 --------------- module 1 ---------------
• Neia Neutuladh (19/32) Nov 26 2018 The spec says:

Gheorghe Gabriel <knoppy273 live.com> writes:

--------------- module 1 ---------------
abstract class Base {
     protected final typeof(this) a() { return this; }
     protected final typeof(this) b() { return this; }
}

--------------- module 2 ---------------
final class Class : Base {
     this() {
         a(); // ok
         b(); // ok

         a().b(); // error, b() call is not accessible from this 
module
     }
}

Neia Neutuladh <neia ikeran.org> writes:

On Mon, 26 Nov 2018 18:25:11 +0000, Gheorghe Gabriel wrote:
 abstract class Base {
      protected final typeof(this) a() { return this; }
      protected final typeof(this) b() { return this; }
 }

typeof(this) is Base. In any derived class, it will still be Base.

 final class Class : Base {
      this() {
          a().b(); // error, b() call is not accessible from this
 module
      }
 }

The spec says:

 If accessing a protected instance member through a derived class member
 function, that member can only be accessed for the object instance which
 can be implicitly cast to the same type as ‘this’.

a() returns a Base. Base cannot be implicitly cast to Class.

If you need this to work, you can write:

    abstract class Base(T)
    {
        protected T a() { return cast(T)this; }
        protected T b() { return cast(T)this; }
    }
    // in another module:
    class Derived: Base!Derived
    {
        this()
        {
            a().b();
        }
    }

There are a couple other ways to do this.