Templates convariance

[michal.minich at gmail.com]

Thank you for casting solution. It should works perfect for my problem. But
could you explain me how this can mess things up?



In article <e79amd$2kil$1 at digitaldaemon.com>, Tom S says...
>
>Frankly, I wouldn't like to see that 'template covariance' in D. It 
>would mess things up... How about doing something like:
>
>class List(T) {
>     template asList(T1) {
>         .List!(T1) asList() {
>             static if (is(T : T1)) {
>                 return cast(.List!(T1))cast(void*)this;
>             } else {
>                 return null;  // or static assert (false)
>             }
>         }
>     }
>}
>
>
>then you might write:
>
>auto circleList = new List!(Circle);
>auto shapeList  = circleList.asList!(Shape);
>
>
>
>-- 
>Tomasz Stachowiak  /+ a.k.a. h3r3tic +/