Unity Container Multiple Implementations of same interface

Question

I\'m studying up on the unity containers and have a quick question on how to resolve a class\'s construction to multiple different implementations of an interface.

H

Answer 1

The problem is that you are resolving Canvas with the name "GL", but you have not registered Canvas in that way. Unity doesn't propagate the name to dependency resolution, so it won't use the name "GL" when resolving IRenderer.

There are several options to solve this already answered: Resolving named dependencies with Unity

Your question is whether this is a bad practice, or how you can achieve the same results. In my experience, trying to register and resolve multiple instances of the same interface usually leads to messy code. One alternative would be to use the Factory pattern to create instances of Canvas.

Do you need to use your container to resolve Canvas? If you don't have a reason not to, you could simply Resolve your IRenderer and new up a Canvas yourself:

new Canvas(container.Resolve("GL"));

Remember that Unity is just a tool, if it doesn't seem to be capable of doing what you need, you may need a different kind of tool.