Question

I have a code which look something like this. When trying to do a ResolveAll I expected every type registered with the IParserType to yielded from the container instance. But I didn’t get any instance from Unity. Am I assuming or doing something wrong here.

public class ResolveAllDemo
{
    public ResolveAllDemo()
    {
        var container = new UnityContainer();

        container.RegisterInstance<IUnityContainer>(container);
        container.RegisterType<IParser, SuperParser>();
        container.RegisterType<IParser, DefaultParser>();
        container.RegisterType<IParser, BasicParser>();
        //   container.RegisterType<Crawler>();
        container.RegisterType<IParserFactory, UnityParserFactory>();

        foreach (var registeredMember in container.ResolveAll<IParser>())
        {
            LoggingUtility.LogerInstance.Logger.Write(registeredMember);
        }
    }

    #region Resolve Demo

    public interface IParserFactory
    {
        IEnumerable<IParser> BuildParsers();
    }

    public class UnityParserFactory : IParserFactory
    {
        private IUnityContainer _container;

        public UnityParserFactory(IUnityContainer container)
        {
            _container = container;
        }

        public IEnumerable<IParser> BuildParsers()
        {
            return _container.ResolveAll<IParser>();
        }
    }

    public class DefaultParser : IParser
    {
        public override string ToString()
        {
            return "DefaultParser";
        }
    }

    public class BasicParser : IParser
    {
        public override string ToString()
        {
            return "BasicParser";
        }
    }

    public class SuperParser : IParser
    {
        public override string ToString()
        {
            return "SuperParser";
        }
    }

    public interface IParser
    {
    }

    #endregion Resolve Demo
}

Answer 1

You are not registering 3 different implementations of IParser. You create one default mapping IParser -> SuperParser and then overwrite it with IParser -> DefaultParser and then you overwrite it again with IParser -> BasicParser.

If you want to register all three of them you have to provide named registrations like

container.RegisterType<IParser, SuperParser>("Super");
container.RegisterType<IParser, DefaultParser>("Default");
container.RegisterType<IParser, BasicParser>("Basic");

In addition ResolveAll does not include the default mapping (the one without a name). It only resolves those mappings of IParser that were registered as named mappings.