Overloading opCast with multiple types

[Stewart Gordon]

Reiner Pope wrote:
> As we all know, opCast can only have one overload per class, because D 
> doesn't support overloading by return type. That is a really silly 
> limitation, in my opinion. Anyway, I have a solution here: give it a 
> parameter, which is the type (we pass this parameter in the form of a 
> template). Here's the magic:
> 
> class Test
> {
>     int x;
>     Foo myCast(TFoo : Foo)() { static assert(is(TFoo == Foo), "No cast 
> of the required type exists"); return new Foo(x); }
<snip>

Something to this effect has been proposed before.

However, the idea of having to put a static assert in each would make it 
somewhat more cumbersome than it should be.  Moreover, a problem with 
using templates is deciding how the vtbl would work.

There have been a number of proposals for ways to do multiple casts.

http://www.prowiki.org/wiki4d/wiki.cgi?FeatureRequestList

My proposal:

http://tinyurl.com/p2pn4

Stewart.


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