From 58d30a60bcf4c24baea53f847f342b4c1e225c68 Mon Sep 17 00:00:00 2001
From: David Botton <david@botton.com>
Date: Wed, 30 Dec 2020 20:05:48 -0500
Subject: [PATCH] singleton demo

---
 clog-system.lisp        | 11 +++++++++--
 clog.lisp               |  5 +++--
 demos/01-hello.lisp     |  2 +-
 demos/02-singleton.lisp | 22 ++++++++++++++++++++++
 4 files changed, 35 insertions(+), 5 deletions(-)
 create mode 100644 demos/02-singleton.lisp

diff --git a/clog-system.lisp b/clog-system.lisp
index 968c0ee..5522e21 100644
--- a/clog-system.lisp
+++ b/clog-system.lisp
@@ -25,7 +25,7 @@
   (let ((body (make-clog-body connection-id)))
     (funcall *on-new-window* body)))
     
-(defun initialize (on-new-window
+(defun initialize (on-new-window-handler
 		   &key
 		     (host           "0.0.0.0")
 		     (port           8080)
@@ -34,7 +34,7 @@
   "Inititalze CLOG on a socket using HOST and PORT to serve BOOT-FILE as 
 the default route to establish web-socket connections and static files
 located at STATIC-ROOT."
-  (setf *on-new-window* on-new-window)
+  (setf *on-new-window* on-new-window-handler)
   
   (cc:initialize #'on-connect
 		 :host host
@@ -42,6 +42,13 @@ located at STATIC-ROOT."
 		 :boot-file boot-file
 		 :static-root static-root))
 
+;;;;;;;;;;;;;;;;;;;;;;;
+;; set-on-new-window ;;
+;;;;;;;;;;;;;;;;;;;;;;;
+
+(defun set-on-new-window (on-new-window-handler)
+  (setf *on-new-window* on-new-window-handler))
+
 ;;;;;;;;;;;;;;
 ;; shutdown ;;
 ;;;;;;;;;;;;;;
diff --git a/clog.lisp b/clog.lisp
index ba05363..a1908ac 100644
--- a/clog.lisp
+++ b/clog.lisp
@@ -38,8 +38,9 @@ application."
 
 (defsection @clog-system (:title "CLOG System")
   "CLOG Startup and Shutdown"
-  (initialize function)
-  (shutdown   function))
+  (initialize        function)
+  (set-on-new-window function)
+  (shutdown          function))
 
 (defsection @clog-utilities (:title "CLOG Utilities")
   "CLOG utilities"
diff --git a/demos/01-hello.lisp b/demos/01-hello.lisp
index 3b09e14..c240937 100644
--- a/demos/01-hello.lisp
+++ b/demos/01-hello.lisp
@@ -1,6 +1,6 @@
 (defpackage #:clog-user
   (:use #:cl #:clog)
-  (:export hello))
+  (:export start-demo))
 
 (in-package :clog-user)
 
diff --git a/demos/02-singleton.lisp b/demos/02-singleton.lisp
new file mode 100644
index 0000000..232177e
--- /dev/null
+++ b/demos/02-singleton.lisp
@@ -0,0 +1,22 @@
+(defpackage #:clog-user
+  (:use #:cl #:clog)
+  (:export start-demo))
+
+(in-package :clog-user)
+
+(defun start-demo ()
+  "How to allow only one CLOG app to be executed. Normally many browsers can
+can be started with the same app."
+
+  (clog:initialize
+   (lambda (win)
+     (let ((click-target (clog:create-child win "<h1>Hello World!</H1>")))
+       (clog:set-on-click click-target
+	(lambda ()
+	  (clog:create-child win "<p>You Clicked me!</p>")))
+       (clog:set-on-new-window
+	(lambda (win)
+	  (clog:put-br (clog:html-document win)
+		       "Only single connection premitted."))))))
+
+  (clog:open-browser))