System Lookup Interface

[pathunstrom]

Right now, when one system needed another system, there's no good way to do it.

As part of this issue, we should build an interface to allow this.

Considerations:

• Should be non-blocking: A system that doesn't have another system shouldn't lock up and should do its best to keep functioning without the other system.
• Should probably use the existing signalling system to request and respond.
• Consider a simple callback model.

[AstraLuma]

These are the kind of operations that don't require IO, or the IO required is synchronous, so making this API async (with callbacks or coroutines) would have little value without future plans to make more of the system async.

This also comes up in other ways:

• Wiring up the sound system
• Camera's viewport and Renderer's window coordination
• System information interrogation (eg, how many mouse buttons there are or what shape of gamepad there is)

[AstraLuma]

An idea that's been floating around is registering systems (or API proxies) onto events, making them accessible to all event handlers.

While this technique hasn't been used yet, it's an option to implement this?

[pathunstrom]

This has come back up with discussion of dependency injection needs. Still needed, design still isn't finished.

[AstraLuma]

I think we call this "dependency injection".