namespace System.Web.Mvc{    public static class HtmlHelperExtensions    {        public static MvcHtmlString BsTextBoxFor<TModel, TProperty>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TProperty>> expression, string placeholder,string @class)        {            TagBuilder tagBuilder = new TagBuilder("input");            ModelMetadata metadata = http://www.mamicode.com/ModelMetadata.FromLambdaExpression(expression, htmlHelper.ViewData);"name", name, true);            tagBuilder.MergeAttribute("type", "text");            tagBuilder.MergeAttribute("placeholder", placeholder);             tagBuilder.MergeAttributes<string, object>(htmlHelper.GetUnobtrusiveValidationAttributes(name, metadata));             tagBuilder.AddCssClass(@class);            return new MvcHtmlString(tagBuilder.ToString());        }    }}