Parameterize object with enum

I'm using C# and Unity Dependency Injection for developing a MVVM application in WPF. I'm looking for a cleanest solution for a following problem.

Some of my classes are parametrized with enums, for example, I have a class AudioChannelViewModel (let's call it for short A) and I want to register two instances of the class, one for Channel.Left and one for Channel.Right. This alone is not a problem, because I register those instances by naming them in RegisterType and then referring to them later by [Dependency(name)] attribute.

Moreover, A depends on some other classes, lets call them Dep1, Dep2 and Dep3. To perform the initialization of A, I must have ALL of my dependencies and 开发者_Python百科the information about the Channel.

I tried to use the following strategies:

1. Property injection of Dep1, Dep2 and Dep3 and setting A's Channel in constructor by RegisterType with InjectionConstructor parameter. But how should I know when A is ready to be initialized? AFAIK I cannot assume anything about the property injection order.

2. Constructor injection of all four items. It would be IMHO the cleanest solution, as I would be able to perform initialization in constructor. But I'm unable to get this working in Unity. Registering A with InjectionConstructor param for Channel throws an exception, and registering with four InjectionConstructor params seems ugly.

3. Constructor injection of Dep1, Dep2 and Dep3 and property injection of Channel. Then I can initialize my class in the Channel setter. It works for this case, but what if A would be parametrized by more than one property? Then I wouldn't know when A is fully built up and ready for initialization.

How should the initialization be performed? Or maybe I'm making things overly complicated.

You don't say exactly what the exception was that you observed in strategy #2, but this is the approach I would be using (given your other requirements for being able to other initialisation having had all the dependencies successfully resolved). I suspect the problem is that you aren't providing a 'value' for all of the arguments of the constructor... InjectionConstructor assumes the constructor you want is the one matching the types of the values provided to the InjectionConstructor.

E.g. if you want to register a constructor for such a class...

public class AudioChannelViewModel {
  public AudioChannelViewModel(Channel channel, Dep1 dep1, Dep2 dep2, Dep3 dep3) {
    ...
  }
}

You should register it thus...

container.RegisterType<AudioChannelViewModel>("left", 
    new InjectionConstructor(Channel.Left,
      typeof(Dep1), typeof(Dep2), typeof(Dep3)));
container.RegisterType<AudioChannelViewModel>("right", 
    new InjectionConstructor(Channel.Right,
      typeof(Dep1), typeof(Dep2), typeof(Dep3)));

Unity will use the provided value for the first argument (a Channel enum value) and will then resolve the Dep1, Dep2 and Dep3 instances. You can also use ResolvedParameter<T> as an argument to InjectionConstructor if there were specific named instances of Dep1, Dep2 or Dep3 that you require.

Just providing Channel.Left or Channel.Right alone is insufficient, as Unity will believe it is being asked to use a constructor with just a Channel argument.

Or; if you HAVE already tried that and it isn't working... maybe Unity doesn't support enums in this instance (pun intended).

This MSDN page might shine some more light on the issue.