As I played with the example, I noticed that the way you register the listener in your .CFM page doesn’t allow me to “unregister” it using that method in the “observable” object. But if I instead create the object separately, then refer to it’s variable name in the “registerObserver” method, I could then unregister and reregister it with no problems:

< cfscript>
userList = CreateObject("component","UserList");
userListLogger = CreateObject("component", "UserListLogger");
userList.registerObserver(userListLogger);
userList.addCustomer( "Larry" );
userList.addCustomer( "Moe" );
userList.unregisterObserver(userListLogger);
userList.addCustomer( "Shemp" );
userList.registerObserver(userListLogger);
userList.addCustomer( "Curly" );
< /cfscript>

This would output:

Larry added to the user list
Moe added to the user list
Curly added to the user list

Thanks again for making this make sense to me!