Add One shot systems

[delaneyj]

Would be nice for setup to have some systems run initialize then remove self

[mlange-42]

Hi @delaneyj!

thanks for coming along!

You can easily do this yourself, as the systems are accessible as the resource Systems.
About like this (not tested):

func (s *MySys) Initialize(world *ecs.World) {
    // Do your stuff...

    sysRes := generic.NewResource[model.Systems](world)
    systems := sysRes.Get()
    systems.RemoveSystem(s)
}

[delaneyj]

Right, I just thought it might be clearer to have a OneShot intereface that only has Init and a System interface extends that interface to be more explicit and to auto handle to removal.

[mlange-42]

Well, ok, this is worth a consideration.