Multiple alias this is coming.

[IgorStepanov via Digitalmars-d-announce]

On Friday, 19 September 2014 at 18:49:57 UTC, Jesse Phillips 
wrote:
> On Thursday, 18 September 2014 at 20:11:12 UTC, IgorStepanov 
> wrote:
>> Do you ask about alias this or about it multiple usage. 
>> Multiple usage is similar to single, but multiple:)
>
> Just an FYI, bearophile is very knowledgeable about D and one 
> of the oldest community members, he holds the record for most 
> bugs opened.
>
> This doesn't mean he knows everything, but it certainly makes 
> it clear he was asking, "why would you want to use multiple 
> alias this." As others mention kind of like "why would you want 
> to use multiple inheritance."


Sorry, I'll note it.:)

>why would you want to use multiple inheritance.

I've written example with interface inherinatce.
Structs can be preferable then classes, when I want to manage 
them allocating manually. When you use D as "better C", powerfull 
struct's can be a you choise.

Multiple alias this (and therefore multiply inheritance) makes 
structs almost as powerful as classes.

Another my motivation of doing this work is a implementing alias 
this inheritance (from base class).
Situation when B can be casted to C and D, A can be casted to B 
and C but cannot be casted to D is wrong:

class B : C
{
    alias d this;
    D d;
}

class A : B
{
}

A a = new A;
D d = a; //NG -> OK