Registering Multiple Mappings of the Same Lookup Type in StructureMap for Constructor Injection

Question

So I have a situation where I want to register n mappings of a particular lookup type. IE:

x.For<IWidget>().Add<SquareWidget>();
x.For<IWidget>().Add<YellowWidget>();

And I want to have SM inject an enumerable (Or array) of them into the constructor of a class:

public class Machine
{
    public Machine(IEnumerable<IWidget> widgets) { ... }
}

ObjectFactory.GetInstance<Factory>()

I'm not seeing a way to do this but I'm might be missing something.

TIA,

m

PS: Please don't respond with "why are you doing it this way" or other non relevant comments. I realize this can be accomplished using other approaches. I'm really just curious if this particular approach is possible. :)

Answer 1

If you had an array of IWidgets in the constructor, then SM would add all IWidgets when you new a Machine, as I believe it's default behavior.

To inject a specific array:

For<IMachine>()
    .TheDefault.Is.OfConcreteType<Machine>()
    .TheArrayOf<IWidget>().Contains(
            x => {
                x.OfConcreteType<SquareWidget>();
                x.OfConcreteType<YellowWidget>();
                x.OfConcreteType<BadWidget>();
            });

or, for an IEnumerable:

For<IMachine>()
    .TheDefault.Is.OfConcreteType<Machine>()
    .CtorDependency<IEnumerable<IMachine>>().Is(i => {
        i.Is.ConstructedBy(c => {
            return new List<ITask> { 
                x.OfConcreteType<SquareWidget>();
                x.OfConcreteType<YellowWidget>();
                x.OfConcreteType<BadWidget>();
                };
             });
     });

There's probably a way to do this last one without having to be specific, but my mind balks. :)

Oh, and injection magic would be possible too.

Answer 2

With more recent versions of StructureMap (which recognize IEnumerable), it should work exactly how you have it in the question. Just register multiple concrete types using For().Add(), and then put an IEnumerable of the interface type as a constructor parameter. StructureMap will automatically inject all of the registered concrete types. No need to use specific registration code like TheArrayOf...