unofficial mirror of emacs-devel@gnu.org 
 help / color / mirror / code / Atom feed
From: Stefan Monnier <monnier@iro.umontreal.ca>
To: Eli Zaretskii <eliz@gnu.org>
Cc: "Basil L. Contovounesios" <contovob@tcd.ie>,  emacs-devel@gnu.org
Subject: Re: Searching for line beginning
Date: Sun, 14 Aug 2022 13:24:31 -0400	[thread overview]
Message-ID: <jwvilmun3l9.fsf-monnier+emacs@gnu.org> (raw)
In-Reply-To: <83pmh2kfaj.fsf@gnu.org> (Eli Zaretskii's message of "Sun, 14 Aug 2022 18:36:52 +0300")

Eli Zaretskii [2022-08-14 18:36:52] wrote:
>> From: "Basil L. Contovounesios" <contovob@tcd.ie>
>> Cc: emacs-devel@gnu.org
>> Date: Sun, 14 Aug 2022 18:33:00 +0300
>> 
>> Eli Zaretskii [2022-08-13 18:43 +0300] wrote:
>> 
>> > C-a (move-beginning-of-line) does this to find the line's beginning:
>> >
>> >     ;; Move to beginning-of-line, ignoring fields and invisible text.
>> >     (skip-chars-backward "^\n")
>> >     (while (and (not (bobp)) (invisible-p (1- (point))))
>> >       (goto-char (previous-char-property-change (point)))
>> >       (skip-chars-backward "^\n"))
>> >
>> > Apart of the fields part (which can be handled by binding
>> > inhibit-field-text-motion), can anyone see a reason why not use
>> > line-beginning-position instead?  The latter is much faster,
>> > especially when lines are very long.
>> 
>> FWIW, one could also say (beginning-of-line) or (beginning-of-line 1)
>> instead of (goto-char (line-beginning-position)).
>
> As a matter of principle, I don't like calling commands from Lisp if I
> can avoid that, because commands frequently have extensive checks of
> the arguments that are redundant in non-interactive calls.

I also like to avoid moving point when it's possible/easy (my original
motivation was to avoid the extra tricky semantics of moving point in
the presence of things like `point-entered` and `intangible` properties,
but even with `inhibit-point-motion-hooks` permanently set to t I think
it's preferable not to move point when given the choice).

In the above loop, it seems it's easy not to move point.


        Stefan




      parent reply	other threads:[~2022-08-14 17:24 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-08-13 15:43 Searching for line beginning Eli Zaretskii
2022-08-13 16:20 ` Stefan Monnier
2022-08-13 17:58   ` Eli Zaretskii
2022-08-14 12:54   ` Eli Zaretskii
2022-08-14 15:33 ` Basil L. Contovounesios
2022-08-14 15:36   ` Eli Zaretskii
2022-08-14 15:43     ` Lars Ingebrigtsen
2022-08-14 15:48       ` Eli Zaretskii
2022-08-15  4:28         ` Lars Ingebrigtsen
2022-08-15 11:29           ` Eli Zaretskii
2022-08-15 11:37             ` Lars Ingebrigtsen
2022-08-15 12:00               ` Eli Zaretskii
2022-08-17  2:49                 ` Richard Stallman
2022-08-17 10:41                   ` Lars Ingebrigtsen
2022-08-17 11:48                   ` Eli Zaretskii
2022-08-17 11:52               ` Stefan Monnier
2022-08-18 12:37                 ` Lars Ingebrigtsen
2022-08-14 17:24     ` Stefan Monnier [this message]

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

  List information: https://www.gnu.org/software/emacs/

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=jwvilmun3l9.fsf-monnier+emacs@gnu.org \
    --to=monnier@iro.umontreal.ca \
    --cc=contovob@tcd.ie \
    --cc=eliz@gnu.org \
    --cc=emacs-devel@gnu.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
Code repositories for project(s) associated with this public inbox

	https://git.savannah.gnu.org/cgit/emacs.git

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).