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public partial class _Default : System.Web.UI.Page { protected void Page_Load( object sender, EventArgs e) { if ( ! IsPostBack) { Assembly ass = Assembly.LoadFile( @" D:\com.uuu9.api.dll " ); DebuggableAttribute att = Utils.GetCustomAttribute < DebuggableAttribute > (ass); Response.Write(att.IsJITTrackingEnabled ? " Debug " : " Release " ); } } } public static class Utils { public static T GetCustomAttribute < T > ( this ICustomAttributeProvider provider) where T : Attribute { var attributes = provider.GetCustomAttributes( typeof (T), false ); return attributes.Length > 0 ? attributes[ 0 ] as T : default (T); } }