Setup process for etags-regen-mode (Emacs 30.0.91 feedback)

Setup process for etags-regen-mode (Emacs 30.0.91 feedback)

[Morgan Willcock]

When testing etags-regen-mode in the Emacs 30 pre-release I've found it
to be working well for my use-case, but one thing which appears to be
missing is an easy way for additional completion functions to opt-in to
the etags-regen-mode setup process.

Currently the completion functions which get advice added to them (to
call etags-regen--maybe-generate) are hard coded in the mode definition:

  (if etags-regen-mode
        (progn
          (advice-add 'etags--xref-backend :before
                      #'etags-regen--maybe-generate )
          (advice-add 'tags-completion-at-point-function :before
                      #'etags-regen--maybe-generate))
      (advice-remove 'etags--xref-backend #'etags-regen--maybe-generate)
      (advice-remove 'tags-completion-at-point-function #'etags-regen--maybe-generate)
      (etags-regen--tags-cleanup))

I was looking for a stable entry point to opt-in to using it, rather
than having to do something like this:

  (advice-add 'my-completion-function-which-does-things-with-tags :before
              #'etags-regen--maybe-generate)

(Where the "--" in the function name is a sign that I probably shouldn't
be doing that.)

I wasn't sure whether it was intentional to hard-code the functions to
advise while etags-regen-mode was still so new, or whether opting in
other functions hadn't been considered.

Would it be possible to store the completion functions which will be
advised as a separate list, so that other packages can add completion
functions to that list and get the TAGS generation to trigger?  Or is
this an intentional boundary?

Thanks,
Morgan

-- 
Morgan Willcock

Re: Setup process for etags-regen-mode (Emacs 30.0.91 feedback)

[Dmitry Gutov]

Hi!

On 20/09/2024 21:14, Morgan Willcock wrote:
> When testing etags-regen-mode in the Emacs 30 pre-release I've found it
> to be working well for my use-case, but one thing which appears to be
> missing is an easy way for additional completion functions to opt-in to
> the etags-regen-mode setup process.
> 
> Currently the completion functions which get advice added to them (to
> call etags-regen--maybe-generate) are hard coded in the mode definition:
> 
>    (if etags-regen-mode
>          (progn
>            (advice-add 'etags--xref-backend :before
>                        #'etags-regen--maybe-generate )
>            (advice-add 'tags-completion-at-point-function :before
>                        #'etags-regen--maybe-generate))
>        (advice-remove 'etags--xref-backend #'etags-regen--maybe-generate)
>        (advice-remove 'tags-completion-at-point-function #'etags-regen--maybe-generate)
>        (etags-regen--tags-cleanup))
> 
> I was looking for a stable entry point to opt-in to using it, rather
> than having to do something like this:
> 
>    (advice-add 'my-completion-function-which-does-things-with-tags :before
>                #'etags-regen--maybe-generate)
> 
> (Where the "--" in the function name is a sign that I probably shouldn't
> be doing that.)
> 
> I wasn't sure whether it was intentional to hard-code the functions to
> advise while etags-regen-mode was still so new, or whether opting in
> other functions hadn't been considered.

Hadn't been considered yet, but I'm open to the idea. Two basic 
approaches is either through a new custom variable, or by making the 
function "public".

The latter is a bit tricky because then we'd need to document what it 
does - and it basically launches all the work ((re)scanning the table, 
adding the hooks), and that setup might change over time.

> Would it be possible to store the completion functions which will be
> advised as a separate list, so that other packages can add completion
> functions to that list and get the TAGS generation to trigger?  Or is
> this an intentional boundary?

The custom variable approach seems better, but we'll need to test how it 
interacts with being able to switch etags-regen-mode on by default.

Re: Setup process for etags-regen-mode (Emacs 30.0.91 feedback)

[Morgan Willcock]

Dmitry Gutov <dmitry@gutov.dev> writes:

>> I wasn't sure whether it was intentional to hard-code the functions to
>> advise while etags-regen-mode was still so new, or whether opting in
>> other functions hadn't been considered.
>
> Hadn't been considered yet, but I'm open to the idea. Two basic
> approaches is either through a new custom variable, or by making the
> function "public".
>
> The latter is a bit tricky because then we'd need to document what it
> does - and it basically launches all the work ((re)scanning the table,
> adding the hooks), and that setup might change over time.
>
>> Would it be possible to store the completion functions which will be
>> advised as a separate list, so that other packages can add completion
>> functions to that list and get the TAGS generation to trigger?  Or is
>> this an intentional boundary?
>
> The custom variable approach seems better, but we'll need to test how it
> interacts with being able to switch etags-regen-mode on by default.

Hi Dmitry,

I'm not in any great hurry to start wiring functions into it, and
waiting for more feedback before adding integration features seems the
logical thing to do.

Thank you for the explanation (and for creating the mode).

Morgan

-- 
Morgan Willcock