using System;

using Microsoft.Practices.Unity;

public class Program

{

    public static void Main()

    {

        var container = new UnityContainer();

        container.RegisterType<IMyInterface, ClassB>();

        container.RegisterType<IMyInterface, ClassC>();

        container.RegisterType<IMyInterface, ClassA>(new InjectionConstructor(new ResolvedParameter(typeof(ClassB))));

        container.RegisterType<IMyInterface, ClassD>();

        var classA = container.Resolve<ClassA>();

        Console.WriteLine("Resolved to: "+classA);

        var myInterface = container.Resolve<IMyInterface>();

        Console.WriteLine("Resolved to: "+myInterface);

    }

}

​

public interface IMyInterface

{

    void PushToDatabase();

}

​

public class ClassA : IMyInterface

{

    public ClassA(IMyInterface myInterface)

    {

        Console.WriteLine("Constructor of ClassA was injected with: "+myInterface);

    }

​

    public void PushToDatabase()

    {

    }

}

​

public class ClassB : IMyInterface

{

    public void PushToDatabase()

    {

        //Actual insert on database

    }

}

​

public class ClassC : IMyInterface

{

    public void PushToDatabase()

    {

        //Actual insert on database

    }

}

public class ClassD : IMyInterface

{

    public void PushToDatabase()

    {

        //Actual insert on database

    }

}