Re: Add/remove an element into/from a cons.

[Hongyi Zhao]

On Thu, Oct 28, 2021 at 12:14 PM Hongyi Zhao <hongyi.zhao@gmail.com> wrote:
>
> On Thu, Oct 28, 2021 at 2:52 AM Tassilo Horn <tsdh@gnu.org> wrote:
> >
> > Hongyi Zhao <hongyi.zhao@gmail.com> writes:
> >
> > >> > However, I can imagine that you might not be able to use it in
> > >> > major-mode hooks such as `emacs-lisp-mode' due to ordering issues,
> > >> > i.e., I can easily imagine that `company-mode' (and this
> > >> > company-tabnine thingy) is initialized *after* the major-mode hook
> > >> > has run because usually, you activate minor-modes in major-mode
> > >> > hooks.  In that case you would try to remove before the
> > >> > company-tabnine entry has been added to company-backends.
> > >> >
> > >> > That's all just guesswork since I don't use company.
> > >>
> > >> [...]
> > >
> > > I also tried the following snippet, but still failed:
> > >
> > > (defun hz/company-tabnine-remove-company-ispell ()
> > >     (make-local-variable 'company-backends)
> > >     (cond
> > >      (
> > >       (derived-mode-p 'emacs-lisp-mode)
> > >       (setf (alist-get 'company-tabnine company-backends)
> > >             (remove 'company-ispell (alist-get 'company-tabnine
> > > company-backends))))
> > >      (
> > >       t
> > >       (setf (alist-get 'company-tabnine company-backends)
> > >         (append (alist-get 'company-tabnine company-backends)
> > >             '(company-ispell))))))
> > >
> > > (add-hook 'emacs-startup-hook #'hz/company-tabnine-remove-company-ispell)
> >
> > The first cond clause looks good but I don't see why you need the
> > t-clause?  Isn't the thing that company-ispell is part of the default
> > value of the company-tabnine entry of company-backends?  If that's the
> > case, you want to make company-backends buffer-local and remove it in
> > emacs-lisp-mode and derived modes but there is no need to add it again
> > otherwise because the default value won't be altered.  So that'd be:
> >
> > --8<---------------cut here---------------start------------->8---
> > (defun hz/company-tabnine-remove-company-ispell ()
> >   (when (derived-mode-p 'emacs-lisp-mode)
> >     (make-local-variable 'company-backends))
> >     (setf (alist-get 'company-tabnine company-backends)
> >             (remove 'company-ispell
> >                     (alist-get 'company-tabnine company-backends))))
> > --8<---------------cut here---------------end--------------->8---
>
> A very strange result based on the above code is that it will remove
> company-ispell in all modes, say, LaTeX mode. But the following code
> works as expected:
>
> (defun hz/company-tabnine-remove-company-ispell ()
>     (when (derived-mode-p 'emacs-lisp-mode)
>       (setq-local company-backends
>           '((company-tabnine :separate company-capf company-dabbrev
> company-keywords company-files))
>           )))
>
>
> > But most importantly, `emacs-startup-hook' is not the one you want.
> > That runs once after emacs has loaded the init file.  I'm even not sure
> > what buffer is current then.  I guess the most logical hook is
> > `company-mode-hook'.
> >
> >   (add-hook 'company-mode-hook
> >             #'hz/company-tabnine-remove-company-ispell)
>
> This works. Thank you for pointing this out.

The following one, which is based on the idea here [1], also works:

(add-hook 'after-change-major-mode-hook
#'hz/company-tabnine-remove-company-ispell)


[1] 
https://github.com/hlissner/doom-emacs/blob/0869d28483b5d81b818b110af351fd5c4dc04dd9/modules/completion/company/config.el#L66


> > Or maybe there is also some `company-tabnine-*-hook' that runs after
> > that package has done its setup in a buffer?
>
> Unfortunately, it doesn't supply these type hooks.
>
> HZ



-- 
Assoc. Prof. Hongyi Zhao <hongyi.zhao@gmail.com>
Theory and Simulation of Materials
Hebei Vocational University of Technology and Engineering
No. 473, Quannan West Street, Xindu District, Xingtai, Hebei province