// @nuget: Unity -Version 3.5.1404

using System;

using Microsoft.Practices.Unity;

​

interface I<T> { }

​

class C<T> : I<T> { }

​

public class Program

{

    public static void Main()

    {

        var ioc = new UnityContainer();

​

        ioc.RegisterType(typeof(I<>), new OpenGenericTypeFactory(typeof(I<>), typeof(C<>)));

​

        var c = ioc.Resolve<I<double>>();

        Console.WriteLine(c.GetType());

    }

}

​

class OpenGenericTypeFactory : Microsoft.Practices.Unity.InjectionFactory {

    public OpenGenericTypeFactory(Type from, Type to)

        : base((container, type, _) => Create(container, from, to, type))

    {

    }

    private static object Create(IUnityContainer container, Type fromType, Type toType, Type requestedType)

    {

        if (!requestedType.IsGenericType || requestedType.GetGenericTypeDefinition() != fromType)

        {

            throw new Exception($"Injection factory for {fromType}: got type {requestedType} instead.");

        }

​

        Type[] argTypes = requestedType.GetGenericArguments();

​

        var closedGenericTarget = toType.MakeGenericType(argTypes);

        try

        {

            return container.Resolve(closedGenericTarget);

        }

        catch

        {

            throw new Exception($"Failed to resolve type {closedGenericTarget} for requested type {requestedType}");

        }

    }

}

​

​