alias this

[Rob T]

On Friday, 30 November 2012 at 23:11:28 UTC, js.mdnq wrote:
>
> I've seen that, how does it work?
>
> struct A{
>  Sometype val1;
>  int val2;
>  alias val1 this;
>  alias val2 this; //???
> }
>
>
> How can A act both as Sometype and int? (at least without major 
> issues) Does the compiler try to choose the appropriate alias 
> depending on the lvalue or rvalue?

If the D devs really do implement alias this fully, then the 
compiler will have to figure out which call to make based on both 
the return type and also the argument list. If a decision is 
ambiguous then a compiler error results. However to do alias this 
correctly and fully you'll have to effectively implement full 
signature overloading.

A few days back I started a thread asking why full function 
signature overloading was not being considered, which I think 
would be very useful to have, but it looked like the devs did not 
want to implement due to the complications involved (no other 
reason was given than that). IMHO they can do it and should do 
it, and will eventually have to do it, but we'll see. Also for 
some reason no one thought that implementing alias this fully 
would mean implementing full signature overloading, or at least 
implementing all of the things required to implement it.

--rt