using System;

using System.Linq;

using System.Reflection;

using Microsoft.Extensions.DependencyInjection;

public class Program

{

    private static readonly Startup Startup = new Startup();

    public static void Main()

    {

        var serviceNameArgument = "junk";

        var serviceType = Assembly.GetExecutingAssembly().GetType(serviceNameArgument, false, true);

        dynamic greeter = Startup.Build().GetService(serviceType);

        if (greeter != null)

        {

            try 

            {

                Console.WriteLine(greeter.SayHello().Message);

            }

            catch (Microsoft.CSharp.RuntimeBinder.RuntimeBinderException)

            {

                Console.WriteLine("Unsupported type");

            }

        }

    }

}

​

internal class Startup

{

    private readonly IServiceCollection services;

    public Startup()

    {

        services = new ServiceCollection();

        Assembly.GetExecutingAssembly()

            .GetTypes()

            .Where(t => !t.IsAbstract && t.IsAssignableToGenericType(typeof(IGreet<>)))

            .ToList()

            .ForEach(t => services.AddTransient(t));

        services.AddTransient<Junk>();

    }

    public ServiceProvider Build() => services.BuildServiceProvider();

}

​

public interface IGreet<T>

{

    T SayHello();

}

​

public class Junk

{

}

​

public class Apple : IGreet<AppleResult>

{

    public AppleResult SayHello()

    {

        return new AppleResult { Message = "Hello apple" };

    }

}

​

public class AppleResult

{

    public string Message { get; set; }

}

​

public class Orange : IGreet<OrangeResult>

{

    public OrangeResult SayHello()

    {

        return new OrangeResult { Message = "Hello orange" };

    }

}

​

public class OrangeResult

{

    public string Message { get; set; }

}

​

public static class ReflectionExtensions

{

    public static bool IsAssignableToGenericType(this Type givenType, Type genericType)

    {

        var interfaceTypes = givenType.GetInterfaces();

​

        foreach (var it in interfaceTypes)

        {

            if (it.IsGenericType && it.GetGenericTypeDefinition() == genericType)

                return true;

        }

​

        if (givenType.IsGenericType && givenType.GetGenericTypeDefinition() == genericType)

            return true;

​

        var baseType = givenType.BaseType;

        if (baseType == null) return false;

​

        return IsAssignableToGenericType(baseType, genericType);

    }

}