Merge 2 structs together (into a single struct)?

[jfondren]

On Friday, 17 September 2021 at 05:01:36 UTC, james.p.leblanc 
wrote:
> Again, thanks to you and many of the D community with helping 
> to learn and
> appreciate the capabilities of D.  It is nice to be here.

Yeah. The improved joinStruct is nice enough that I think it's 
probably a good thing to do.

And there's this, some kind of Jai innovation:

```d
struct Object {
     float[2] position, velocity, facing;
     float size;
}

struct Player {
     mixin parent!Object;
     int hp;
}

mixin template parent(Struct) {
     static foreach (i, alias f; Struct.tupleof) {
         mixin("typeof(f) ", __traits(identifier, f), " = 
Struct.init.tupleof[i];");
     }
}

void main() {
     import std.stdio : writeln;

     writeln(Player([0, 0], [0, 0], [0, -1], 5.0, 100));
}
```