Optional Injection for MonoBehaviours

[ModischFabrications]

I have a Unity project that builds to a VR + NonVR solution with a shared codebase, but different objects within the scene. I am able to remove objects during building and have no problem checking everything in code.

My problem: VContainer injection cares deeply that [Inject] works and crashes out if not, but I want to have cases like this were I expect (xr) references to be missing.

My proposal:

        [Inject(Optional = true)]
        public void Construct([CanBeNull] TeleportationProvider teleportProvider)
        {
            _teleportProvider = teleportProvider;
        }

My current workaround:

        [Inject]
        public void Construct(IObjectResolver container)
        {
            _container = container;
        }

        private void Start()
        {
            // resolve manually to check if XR is actually there; can't hardcode XR reference injection
            if (_container.TryResolve(out _teleportProvider))
                return;

            Log.Warning("No teleportation provider found; might want to remove from build");
        }

[simon-nordon]

Would it not be better to have 2 different installers for each application? The advantage of DI would be that you can reconfigure your application from the registration level. At the very least you should be injecting an ITeleportationProvider instead, in the VR Project you

builder.Register<TeleportationProvider>(LifetimeScope.Singleton).As<ITeleportationProvider>();

and in your none VR version you would use

builder.Register<DummyTeleportationProvider>(LifetimeScope.Singleton).As<ITeleportationProvider>();

I think the strength of VContainer is that it's opinionated about not letting users break DI Conventions. Rather than changing the framework we should be using it as intended.