Idea: Lazy upcasting

[Marcin Kuszczak]

Reiner Pope wrote:
> 
> How about:
> 
> interface Storage
> {
>      Storage param1(int);
> }
> 
> abstract class StorageImpl(T) : Storage {
>      static assert(is(typeof(this) == T));
> 
>      T param1(int p1)
>      {
>          this.p1 = p1;
>          return cast(T)this;
>      }
>      private int p1;
> }
> 
> class SpecificStorage : StorageImpl!(SpecificStorage) {
>      SpecificStorage param2(bool p2) {
>          this.p2 = p2;
>          return this;
>      }
>      private bool p2;
> }
> 
> That should already work.
> 
> Cheers,
> 
> Reiner

I get problems with compiling this (I put info in another post). But even if
it would work I think that problem should be just fixed not only worked
around. For my own "hot-fix" workaround I used template mixin.

The problem is that solution is just complicated for simple use. It's
*unnecessary* complicated as it can be solved by fixed current clumsy
covariant feature.

Best what could be worked out up till now is in:
http://www.digitalmars.com/webnews/newsgroups.php?art_group=digitalmars.D&article_id=51241

(It's my before previous post.)

-- 
Regards
Marcin Kuszczak (Aarti_pl)
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