I made a little program to illustrate my confusion :

  import std.stdio;

  class _1 {
	  int i;
	
	  this(int n) {
		  i = n;
	  }
  }

  class _2 {
	  _1 instance;
	
	  alias twelve = instance.i;
	
	  this() {
		  instance = new _1(12);
	  }
  }

  void main() {
	  _2 two = new _2();
	  writeln(two.instance.i);
	  writeln(two.twelve);
  }

What i tried to do is create an alias in class _2 of a variable in class _1.
What i would like is :
  two.twelve
to extends to:
  two.instance.i
But the compiler complains it cannot find "this" :
  Error: need 'this' for 'i' of type 'int'

Any ideas?

I guess it's because you're accessing a member of _1 from inside a scope of _2 where nothing has been constructed yet? Someone more familiar with D would probably have a better answer on this part. I'm quite new :)

But a work around would be

class _2 {
	  _1 instance;
	
	  auto twelve() @property {
              return instance.i;
          }
	
	  this() {
		  instance = new _1(12);
	  }
  }

On Tuesday, 13 December 2016 at 19:13:24 UTC, Begah wrote:
> Any ideas?

you can't.

On Tuesday, 13 December 2016 at 19:13:24 UTC, Begah wrote:
> Any ideas?

Closest you can get is wrapping it in a property. If you need to do this often you may be able to generate them, check the recent "Getters/Setters generator" thread in Announce for some inspiration.