C# Online Compiler | .NET Fiddle

using System;
using System.Collections.Generic;

public interface IViewEngine
{
    string Render(string viewName, Dictionary<string, object> context);
}

public class MatchaViewEngine: IViewEngine
{
    public string Render(string viewName, Dictionary<string, object> context)
    {
        return "View Rendered by Matcha";
    }
}

public class SharpViewEngine: IViewEngine
{
    public string Render(string viewName, Dictionary<string, object> context)
    {
        return "View Rendered by Sharp";
    }
}

public class Controller
{
    public void Render(string viewName, Dictionary<string, object> context)
    {
        var viewEngine = CreateViewEngine();
        var html = viewEngine.Render(viewName, context);
        Console.WriteLine(html);
    }

    protected virtual IViewEngine CreateViewEngine()
    {
        return new MatchaViewEngine();
    }
}

public class SharpController: Controller
{
    protected override IViewEngine CreateViewEngine()
    {
        return new SharpViewEngine();
    }
}

public class ProductsController: SharpController
{
    public void ListProducts()
    {
        Dictionary<string, object> context = new Dictionary<string, object>();
        Render("products.html", context);
    }
}


public class Program
{
	public static void Main()
	{
		ProductsController controller = new ProductsController();
		controller.ListProducts();
	}
}

 
using System;
using System.Collections.Generic;
​
public interface IViewEngine
{
    string Render(string viewName, Dictionary<string, object> context);
}
​
public class MatchaViewEngine: IViewEngine
{
    public string Render(string viewName, Dictionary<string, object> context)
    {
        return "View Rendered by Matcha";
    }
}
​
public class SharpViewEngine: IViewEngine
{
    public string Render(string viewName, Dictionary<string, object> context)
    {
        return "View Rendered by Sharp";
    }
}
​

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