test2

gist.cs

 [Extension("This extension enables Github Gist support for BlogEngine.NET.", "1.0", "Cong Danh")]
    public class GistExtension
    {
        public GistExtension()
        {
            Post.Serving += Post_Serving;
        }

        void Post_Serving(object sender, ServingEventArgs e)
        {
            e.Body = Regex.Replace(e.Body, "\\[gist\\s[^\\]]*id=(\\d+)[^\\]]*\\]","<script src=\"https://gist.github.com/$1.js\"></script>");
        }
    }