In my package I have the following:
(defcustom foobar-on-exit t
"Boolean variable, enabled by default."
:type 'boolean
:group 'foobar)
(if foobar-on-exit
(add-hook 'kill-emacs-hook 'some-message))
So I get a message when I close Emacs.
Then in my init.el I set the value of foobar-on-exit on nil.
(setq foobar-on-exit 'nil)
After evaluating or restarting, I still got the message while the variable foobar-on-exit is still false.
So somewhere I went wrong. Any hint?
I believe this is an order-of-evaluation problem. Since the defcustom and the if are both in the package, and the setq is in the init file (presumably some time after the loading of the package), when the package gets loaded (via autoload or otherwise), foobar-on-exit will be set to t, then the if form will be evaluated and some-message will get added to kill-emacs-hook.
The correct sequence of events is defcustom, setq, if. The only way to do that presently is to have both the setq and the if in your init file.
If you want to leave the if in the package, then it needs to be in a function that gets added to kill-emacs-hook, that way the current value of foobar-on-exit will always be used when emacs is killed.
ifstatement is in your package, thenfoobar-on-exitwill betwhen that form is evaluated and the message will be added tokill-emacs-hookregardless of what you do with the variable afterwards. So if your package is loaded (via autoload or otherwise) prior to thesetq, you'll always get the message.init.el, then it will be evaluated afterwards in the package?defcustom,setq,if. The only way to do that is to have thedefcustomin the package, and thesetqandifin your init file. A better way is to put theifin the form that gets added tokill-emacs-hook, so it will always use the current value at shutdown time.ifinto a function, that will do evaluating, and I added that function to a hook. Thanks for your suggestion, it's appreciated. Wish I could mark your answer as the right one.