Re: New version of todo-mode.el (announcement + user guide)

[Stefan Monnier]

> Thank you for this excellent "advice" ;-).  It works very nicely --
> except for one wrinkle: after loading todos.el (which requires
> 'diary-lib) I have to eval diary-goto-entry (or load diary-lib) again in
> order for the advice to take effect.  Without doing that it's as if the
> advice were not activated.  But I see nothing about activating advice in
> nadvice.el.  Here's what I added to diary-lib.el:

Contrary to advice, which has all kinds of subtle distinction between
defining an advice, enabling an advice, and activating an advice,
nadvice just has add-function (or advice-add) which
works more like add-hook (i.e. kind of defines/enables/activates all at
once).

> (define-derived-mode todos-mode special-mode "Todos"
>   "Major mode for displaying, navigating and editing Todo lists.

> \\{todos-mode-map}"
> ;; other initializations ...
>   (add-function :around diary-goto-location-function
>               (lambda (orig-fun &rest args)
>                 (when (derived-mode-p 'todos-mode) (widen))
>                 (apply orig-fun args)
>                 (todos-diary-goto-entry))))

This doesn't make sense: you `add-function' to the global value of
diary-goto-location-function, but you do it in the mode function,
i.e. once per todo-mode buffer.

Either do it locally (i.e. in the todo-mode function but with

   (add-function :around (local diary-goto-location-function)
                (lambda (orig-fun &rest args)
                  (widen)
                  (apply orig-fun args)
                  (todos-diary-goto-entry)))

Or do it globally, (i.e. at the top-level of todo-mode.el).


        Stefan