Multiple alias this, what's the hold up?

[Olivier FAURE]

On Monday, 17 June 2019 at 17:41:07 UTC, Ethan wrote:
> The implication here also is that component-based programming 
> is not a method that the games industry is going to drop any 
> time soon. If you're doing console game development, you need 
> to be familiar with how to use components.

I agree with you that D has great potential as tool to write an 
Entity-Component-System architecture better than existing 
languages (for instance, it can swap arrays-of-structs with 
structs-of-arrays pretty seamlessly), but I don't follow how 
`alias this` is necessary or even helpful for ECS?

All use cases I've seen could be handled idiomatically with 
`static foreach`, `static if` and `__traits(hasMember, ...)`.

Functions meant for an idiomatic ECS framework would look like:

     @needs_components(Health, DamageToken)
     @optional_components(ArmorSystem)
     @needs_tags("!immortal")
     void system_applyDamage(int entityId, ref Health, ref 
DamageToken, ArmorSystem*)
     {
         ...
     }

No recompilation needed, expresses exactly what it does. I don't 
think you need `alias this` at all.