Re: Introducing face in comments for various modes

[Heime]

------- Original Message -------
On Tuesday, December 13th, 2022 at 10:45 AM, Thibaut Verron 
<thibaut.verron@gmail.com> wrote:


> On 13/12/2022 11:40, Heime wrote:
> 
> > ------- Original Message -------
> > On Tuesday, December 13th, 2022 at 10:05 AM, Thibaut Verron 
> > thibaut.verron@gmail.com wrote:
> > 
> > > On 13/12/2022 10:46, Heime wrote:
> > > 
> > > > ------- Original Message -------
> > > > On Tuesday, December 13th, 2022 at 9:35 AM, Thibaut Verron 
> > > > thibaut.verron@gmail.com wrote:
> > > > 
> > > > > On 13/12/2022 09:30, Heime wrote:
> > > > > 
> > > > > > ------- Original Message -------
> > > > > > On Tuesday, December 13th, 2022 at 8:04 AM, Heime 
> > > > > > heimeborgia@protonmail.com wrote:
> > > > > > 
> > > > > > > ------- Original Message -------
> > > > > > > On Tuesday, December 13th, 2022 at 7:52 AM, Jean Louis 
> > > > > > > bugs@gnu.support wrote:
> > > > > > > 
> > > > > > > > Heime, I like the idea of highlighting comments, though I do it 
> > > > > > > > this
> > > > > > > > way to specify (syntax comment-start) as that works for multiple
> > > > > > > > modes.
> > > > > > > > 
> > > > > > > > ; one
> > > > > > > > ;; two
> > > > > > > > ;;; three
> > > > > > > > ;;;; and more
> > > > > > > > 
> > > > > > > > ;;; Highlighting comments
> > > > > > > > 
> > > > > > > > (setq rcd-regexp-comment (rx line-start
> > > > > > > > (one-or-more (syntax comment-start))
> > > > > > > > (one-or-more space)
> > > > > > > > (group (one-or-more not-newline))
> > > > > > > > line-end))
> > > > > > > > 
> > > > > > > > ;; (highlight-regexp regexp nil 1)
> > > > > > > > ;; (unhighlight-regexp regexp)
> > > > > > > > 
> > > > > > > > Jean
> > > > > > > > I would like to introduce (syntax comment-start) in place
> > > > > > > > of ";;" in "^;;\s+\\[.+\\].*$".
> > > > > > > > It's not something you can "introduce" in your regexp, it only 
> > > > > > > > makes
> > > > > > > > sense within the context of a regexp built with rx:
> > > > > > > > https://www.gnu.org/software/emacs/manual/html_node/elisp/Rx-Notation.html
> > > > > 
> > > > > Rewriting your regexp as an rx regexp would not be too difficult if 
> > > > > you
> > > > > want to go that route, Jean's example is a good template.
> > > > > 
> > > > > Otherwise, as an approximation of that feature, you could built your
> > > > > regex string using the value of the variable comment-start ( ";" in
> > > > > emacs-lisp-mode) instead of hardcoding ;; .
> > > > > How can one specify two comment characters next to each other?
> > > 
> > > Using the variable, the same way you would normally do for a regexp, by
> > > putting \{2\} after the matched regexp.
> > > 
> > > E.g.
> > > 
> > > ELISP> (format "\\(%s\\)\\{2\\}" comment-start)
> > > 
> > > "\\(;\\)\\{2\\}"
> > > 
> > > (don't trust me for the number of escape characters)
> > > 
> > > But I don't think it's really what you want: for example, in a mode
> > > where comment-start is "# " (e.g. org or python), this will match "# # "
> > > but not "##".
> > > Let's disregard org and python at this time.
 
I do not think "python" comment character should be "# ", it is "#".  At least 
from what I have read about python. 

 
> Even then, avoiding the need to carefully count string expansions for
> backslashes would be enough reason to use syntax tables for me.
> 
> > > Using the syntax table is better here, as the character # alone has the
> > > syntax of a comment-start.
> > > 
> > > I had forgotten about the simplest option, that is the regexp equivalent
> > > of the rx syntax: \s< in a regexp will match exactly a character with
> > > the syntax of a comment-start.
> > > 
> > > So: "\s<\{2\}" should be exactly what you want (at least in languages
> > > where comments start with a single character).