First Draft: ref For Variable Declarations

[Dennis]

On Wednesday, 17 April 2024 at 14:29:17 UTC, Dukc wrote:
> If that was the case this DIP would be completely useless, as 
> you could already do everything it enabled with `alias`.

I currently sometimes use pointers to alias members.

```D
// Inside struct LightOptimizer
void moveLightGlobal()
{
     auto light = &this.scene.light;
     light.pos += vec3(...);
}

void onMouseclick(ref GameState gs)
{
     auto ui = &gs.ui;
     ui.startDrag();
     ...
}
```

I'd prefer using `ref` since that's safer and enables opIndex 
overloads, so this DIP seems like a nice addition to me. I tried 
replacing those cases with alias but it errors:
```
Error: accessing non-static variable `scene` requires an instance 
of `LightOptimizer`
```