[emacs-berlin] A doubt about use-package

[Narendra Joshi]

jman <emacs-berlin at storiepvtride.it> writes:

> Hello folks,
>
> freues neues Jahr :)
>
> I have a question which I can't seem to solve by searching around.
>
> I've found this snippet to configure mu4e (the email client inside
> emacs) [0] so I copied some parts of it but they don't seem to
> work. In fact, they do look wrong to me.
>
> Just an example:
>
> (use-package mu4e
>  ...
>  :custom
>  (mu4e-attachment-dir "~/Downloads")
>  ...
>
> it just doesn't work for me, I need to instead move each command to the
> `:init` to make it work:
>
> (use-package mu4e
>  ...
>  :init
>  (setq mu4e-attachment-dir "~/Downloads")
>  ...

--8<---------------cut here---------------start------------->8---
(use-package mu4e
 ...
 :custom
 (mu4e-attachment-dir "~/Downloads"))

--8<---------------cut here---------------end--------------->8---

macro-expands to (try `pp-macroexpand-last-sexp', I use `macrostep-mode'
for quickly checking macro expansions in the same buffer).

--8<---------------cut here---------------start------------->8---
......
        (funcall
         (or
          (get 'mu4e-attachment-dir 'custom-set)
          #'set-default)
         'mu4e-attachment-dir "~/Downloads")
......
--8<---------------cut here---------------end--------------->8---

`set-default` here is going to set the top-level (i.e. outside all let
bindings and buffers [for buffer local variables]) value.

`defcustom` will not change the value of a variable that already has a
top-level value. If you are trying to check this (with C-x C-e), try
something like:

--8<---------------cut here---------------start------------->8---
(eval '(defcustom mu4e-attachment-dir "~/Downloads" "Docstring"))
--8<---------------cut here---------------end--------------->8---

That's because C-x C-e (`eval-last-sexp') handles `defvar' and
`defcustom' differently during interactive use. If these are in a file
which is loaded, they are evaluated differently.


Getting back to your problem, I think you probably have a `set{q}`
somewhere that is causing this issue. Whenever I face similar problems,
the first file that I check for interfering bindings is the
`custom-file'. If you have not explicitly set the `custom-file'
variable, your init file will contain these, probably at the end of the
file.

To debug this problem, setting a variable watcher at the beginning of
your init.el might help:

--8<---------------cut here---------------start------------->8---
(add-variable-watcher 'the-var-to-be-watched
                      (lambda (sym new-value operation where)
                          (message "Value for %s getting modified to %s with %s in buffer %s"
                                   sym new-value operation where)))

--8<---------------cut here---------------end--------------->8---

Best regards,
> This applies for any variable in that code. I need to use `setq`,
> otherwise it is not loaded. If I check the value with `C-h v` it doesn't
> pick up my customization. If I check it with `M-x customize-variable`
> emacs says that the variable is "CHANGED outside Customize" but I don't
> see any effect.
>
> I'm sure I'm missing something here so, It's driving me nuts :)
>
> thanks for any hint!
>
> ein lieben Grüß,
>
> [0] https://github.com/adimit/config/blob/7aa03bda553ad3cbddc1976c431427f1586c0=7b8/newmacs/main.org#mu4e
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>

--
Narendra Joshi