Is there a reverse function of axlSessionRegisterCreationCallback, i.e. axlSessionUnRegisterCreationCallback ?

There's no function to unregister the session creation callback.

Of course, what you can do is have the function registered with axlSessionRegisterCreationCallback conditionally call axlSessionConnect to only register the signal callbacks you want to be triggered in the newly created session. Or you could have the triggers always connected and then conditionally do something within them or not.

Andrew

Thanks Andrew for such an obvious answer~ What was I thinking in the first place? The solution is so straight forward. Thank you so much!

Is there any shortcomings that you could think off using either approaches?

The most obvious benefit I see in the second approach is that when the session is already created, it can take effect immediately if you change the condition. Where as the first approach can only take effect after a new session is started when the condition change.

;register a callback to connect the triggers on ADE XL session start
(axlSessionRegisterCreationCallback 'ADEXLTriggers_func1)
(axlSessionRegisterCreationCallback 'ADEXLTriggers_func2)

;connect ADE XL triggers
(defun ADEXLTriggers_func1 (session)
if(boundp('myVar) && myVar!=nil then
(axlSessionConnect session "postInstall" 'func1)
(axlSessionConnect session "postCreatedTest" 'func1)
(axlSessionConnect session "preRun" 'func1)
else
(axlSessionDisconnect session 'func1)
)
)

(defun ADEXLTriggers_func2 (session)
(axlSessionConnect session "postInstall" 'func2)
(axlSessionConnect session "postCreatedTest" 'func2)
(axlSessionConnect session "preRun" 'func2)
)

;define a handler to connect to a trigger
procedure( func1(session @rest args)
let(()
printf("Func1: Length of arguments: %d\n" length(args))
); let
); procedure
procedure( func2(session @rest args)
let(()
if(boundp('myVar) && myVar!=nil then
printf("Func2: Length of arguments: %d\n" length(args))
); if
); let
)

In terms of efficiency it's unlikely to make any noticeable difference - I'd probably default to the first approach unless I needed the ability to change the behaviour during the session (as you said).

Note that in ADEXLTriggers_func1 you don't need the axlSessionDisconnect call - the functions won't be connected to the signal unless you connected them in the first place for that session, which won't have happened since you're in the session creating callback.

Regards,

Andrew

Apologies for the late response as I was OOO. Thanks Andrew for the advice. You are correct. ADEXLTriggers_func1  is only register during session setup. So there's no need for the 'else' condition to disconnect. You have fully answer my query.