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, object htmlAttributes = null)
    {
        var tag = useAnchor ? "a" : "span";
        var tagBuilder = new TagBuilder(tag);

        tagBuilder.MergeAttributes(HtmlHelper.AnonymousObjectToHtmlAttributes(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));
    }
}