SharePoint: Code for extending a web app

This doesn't claim to be the code to extend a web app, but more like a boilerplate that you can adapt to your own needs. I tried it with a generous matrix of parameters and works correctly, but I have no doubt that some combinations may cause issues.

        private static void ExtendWebApplication(SPWebApplication webapp, string name, int port, SPUrlZone zone, bool secure, bool useWindowsAuth, bool allowAnonymous, bool useClaims)
        {
            if (webapp == null)
            {
                throw (new ArgumentNullException("webapp"));
            }

            SPServerBinding serverBinding = null;
            SPSecureBinding secureBinding = null;
            if (secure)
            {
                secureBinding = new SPSecureBinding();
                secureBinding.Port = port;
            }
            else
            {
                serverBinding = new SPServerBinding();
                serverBinding.Port = port;
            }

            string extendedAppPath = webapp.IisSettings[SPUrlZone.Default].Path.ToString().Substring(0, webapp.IisSettings[SPUrlZone.Default].Path.ToString().LastIndexOf(@"\") + 1) + port.ToString();
            SPIisSettings iisSettings = new SPIisSettings(
                string.Format(CultureInfo.InvariantCulture, "{0} - {1}", name, port),
                false,
                true,
                serverBinding,
                secureBinding,
                new DirectoryInfo(extendedAppPath));
            iisSettings.DisableKerberos = !useWindowsAuth;
            iisSettings.UseWindowsIntegratedAuthentication = useWindowsAuth;
            iisSettings.AllowAnonymous = allowAnonymous;
            webapp.IisSettings.Add(zone, iisSettings);
            webapp.AlternateUrls.SetResponseUrl(new SPAlternateUrl(GetAlternateUrl(port, secure), zone));
            webapp.AlternateUrls.Update();
            webapp.UseClaimsAuthentication = useClaims;
            webapp.Update();
            webapp.ProvisionGlobally();
        }