HtmlHelper extension to toggle between span & anchor easily

Spanchor

    using System;
    using System.Collections.Generic;
    using System.IO;
    using System.Web.Mvc;

    public static class SpanchorExtension
    {
        public static Spanchor Spanchor(this HtmlHelper htmlHelper, bool useAnchor, string url, IDictionary<string, object> htmlAttributes)
        {
            var tag = useAnchor ? "a" : "span";
            var tagBuilder = new TagBuilder(tag);

            tagBuilder.MergeAttributes(htmlAttributes);

            if (useAnchor)
            {
                tagBuilder.MergeAttribute("href", url);
            }

            htmlHelper.ViewContext.Writer.Write(tagBuilder.ToString(TagRenderMode.StartTag));
            
            return new Spanchor(htmlHelper.ViewContext, tagBuilder);
        }
    }

    public class Spanchor : IDisposable
    {

        private bool _disposed;
        private readonly TagBuilder _tagBuilder;
        private readonly TextWriter _writer;

        public Spanchor(ViewContext viewContext, TagBuilder tagBuilder)
        {
            if (viewContext == null)
            {
                throw new ArgumentNullException("viewContext");
            }
            if (tagBuilder == null)
            {
                throw new ArgumentNullException("tagBuilder");
            }

            _tagBuilder = tagBuilder;
            _writer = viewContext.Writer;
        }

        public void Dispose()
        {
            Dispose(true /* disposing */);
            GC.SuppressFinalize(this);
        }

        protected virtual void Dispose(bool disposing)
        {
            if (_disposed)
            {
                return;
            }
            _disposed = true;
            _writer.Write(_tagBuilder.ToString(TagRenderMode.EndTag));
        }
    }