Can you have generic create method for Zenject

Question

So I have a base class and some derived classes, I want to have just one factory with generic create method witch will create appropriate instances and inject all dependencies. Is this possible using Zenject? Something like.

factory.Create<Archer>()

For now I am doing this but as you see this is not very clean solution.

 public class CustomFactory : IFactory<Type, BaseUnit>
{
    private DiContainer _container;

    public CustomFactory(DiContainer container)
    {
        _container = container;
    }
    public BaseUnit Create<Type>()
    {
        return null;
    }

    public BaseUnit Create(Type type)
    {
        if (type.BaseType != typeof(BaseUnit))
        {
            Debug.LogError("you cant create objects that are not derrived from base unit");
            return null;
        }

        object obj = _container.Resolve(type) ;
        return _container.InstantiatePrefabForComponent(type, obj as UnityEngine.Object, null, new object[0]) as BaseUnit;
    }
}

Can't you just do `Create() where T: BaseUnit` and then replace all usages of `type` with `typeof(T)` in your method? — Evk, Apr 28 '18 at 07:30

score 1 · Accepted Answer · answered Apr 29 '18 at 07:08

I think the way you have it is probably the easiest way to do this. Here's some minor changes to what you did:

public class UnitFactory
{
    readonly DiContainer _container;
    readonly List<UnityEngine.Object> _prefabs;

    public UnitFactory(
        List<UnityEngine.Object> prefabs,
        DiContainer container)
    {
        _container = container;
        _prefabs = prefabs;
    }

    public BaseUnit Create<T>()
        where T : BaseUnit
    {
        var prefab = _prefabs.OfType<T>().Single();
        return _container.InstantiatePrefabForComponent<T>(prefab);
    }
}

public class TestInstaller : MonoInstaller<TestInstaller>
{
    public FooUnit FooPrefab;
    public BarUnit BarPrefab;

    public override void InstallBindings()
    {
        Container.Bind<UnitFactory>().AsSingle();
        Container.Bind<UnityEngine.Object>().FromInstance(FooPrefab).WhenInjectedInto<UnitFactory>();
        Container.Bind<UnityEngine.Object>().FromInstance(BarPrefab).WhenInjectedInto<UnitFactory>();
    }
}

Only drawback with this approach is that the prefabs will not be validated, so if they have missing injections it won't be caught until runtime. The alternative would be to create individual factories for each BaseUnit, and then inject those factories into UnitFactory, but that would probably get messy

Can you have generic create method for Zenject

1 Answers1