using System;

public class Program

{

    public static void Main()

    {

        FooBarParameters p = new FooBarParameters();

        p.Id = 1;

        FooFactory ff = new FooFactory();

        // Expecting "Bar" as Id = 1

        var result = ff.GetInstance(p);

    }

}

​

public interface IFooParameters

{

    int Id { get; }

}

​

public interface IFooParametersAdditional

{

    int AnotherProperty { get; }

}

​

public class FooBarParameters : IFooParameters

{

    public int Id { get; set; } = 1;

    public int Bar { get; set; } = 42;

}

​

public class FooBazParameters : FooBarParameters, IFooParametersAdditional

{

    public int Baz { get; set; } = 55;

    public int AnotherProperty { get; set; } = 99;

}

​

public interface IFoo<in TFooParameters>

    where TFooParameters : IFooParameters

{

    void DoStuff(TFooParameters parameters);

}

​

public class Bar : IFoo<FooBarParameters>

{

    public void DoStuff(FooBarParameters parameters)

    {

        throw new System.NotImplementedException();

    }

}

​

public class Baz : IFoo<FooBazParameters>

{

    public void DoStuff(FooBazParameters parameters)

    {

        throw new System.NotImplementedException();

    }

}

​

public class Another : IFoo<FooBazParameters>

{

    public void DoStuff(FooBazParameters parameters)

    {

        throw new System.NotImplementedException();

    }

}

​

public interface IFooFactory

{

    IFoo<IFooParameters> GetInstance(IFooParameters parameters);

}

​

public class FooFactory : IFooFactory

{

    public IFoo<IFooParameters> GetInstance(IFooParameters parameters)

    {

        if (parameters.Id == 1)

            return (IFoo<IFooParameters>) new Bar(); // *** compiler error

​

        if (parameters.Id == 2)

            return (IFoo<IFooParameters>) new Baz(); // *** compiler error

​

        return (IFoo<IFooParameters>) new Another(); // *** compiler error

    }

}