gistfile1.txt

using System;

namespace SimplifyVisitor
{
    public class ConcreteVisitor : VisitorBase<Node>
    {
        protected void Visit(ConstantNode node)
        {
            Console.WriteLine("Visiting constant node");
        }

        protected void Visit(PlusNode node)
        {
            Console.WriteLine("Visiting plus node");
        }

        protected void Visit(MinusNode node)
        {
            Console.WriteLine("Visiting minus node");
        }

        protected override void VisitMembers(Node node)
        {
            this.Visit(node);
        }
    }
}

gistfile2.txt

using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace SimplifyVisitor
{
    using System.Reflection;

    public abstract class VisitorBase<T> where T : Node
    {
        public void Dispatch(T node) 
        {
            this.VisitMembers(node);
        }

        protected abstract void VisitMembers(T node);
    }
}