Castle Windsor - resolving dependencies based on class name

Question

Suppose I have registered a number of external dependencies from a folder using the following code:

container.Register(Types.FromAssemblyInDirectory(new AssemblyFilter(""))
    .Where(a = >a.IsSubclassOf(typeof(MyPlugin))));

The code above works fine and I'm able to see all dependencies inheriting MyPlugin in the container. Say I have the classes MyPluginA and MyPluginB inheriting from MyPlugin in the container and I would like to retrieve MyPluginA . How should I go about it?

Thanks

Answer 1

The usual method is to register each implementation with a name, and resolve them using the name. This is how I've done it in the past.

To register plugins in their installers:

container.Register(
    Component.For<MyPlugin>.Named(MyPluginA.ID).ImplementedBy<MyPluginA>());

ID could be the name of the class, or any unique string ID. To resolve, you get Windsor to implement you a factory that can accept an ID. Define the interface:

public interface IPluginFactory
{
    MyPlugin CreatePluginById(String id);
}

Define a component selector that can select plugin IDs provided as the first argument in a constructor:

public class PluginFactorySelector : DefaultTypedFactoryComponentSelector
{
    protected override string GetComponentName(MethodInfo method, object[] arguments)
    {
        return (method.Name.EndsWith("ById") && arguments.Length >= 1 && arguments[0] is string)
            ? (string) arguments[0]
            : base.GetComponentName(method, arguments);
    }
}

Finally, hook it all up in an installer in your application...

container.Register(
    Component.For<PluginFactorySelector, ITypedFactoryComponentSelector>().LifestyleSingleton(),
    Component.For<IPluginFactory>().AsFactory(c => c.SelectedWith<PluginFactorySelector>()));