Re: SumType extraction

[An Pham via Digitalmars-d-learn]

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);