SumType extraction

[An Pham]

On Thursday, 27 June 2024 at 18:51:19 UTC, Josh Holtrop wrote:
> Hello all. In my application I came across a desire to store an 
> ordered array of handles that could point to one of several 
> different objects, and it seems like the tool I want for that 
> is SumType.
>
> I started with something like (simplified of course):
>
> ```d
> class Foo {}
> class Bar {}
>

My Variant package can do this type of thing
https://github.com/apz28/dlang/blob/main/source/pham/var/var_variant.d#L3430

     Variant[] mixedC;
     mixedC ~= new Foo();
     mixedC ~= new Bar();
     size_t foundCount;
     foreach (v; mixedC)
     {
         if (auto c = v.peek!Foo)
         {
             foundCount++;
         }
     }
     assert(foundCount == 1);