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From: Stefan Monnier <monnier@iro.umontreal.ca>
To: help-gnu-emacs@gnu.org
Subject: Re: Operate on each line in region
Date: Wed, 23 Apr 2014 14:05:18 -0400	[thread overview]
Message-ID: <jwvr44ox6yi.fsf-monnier+gmane.emacs.help@gnu.org> (raw)
In-Reply-To: 787a28ce-2ab1-4b11-92fd-ca4506447baa@googlegroups.com

> (defun my-justify (start end)
> (interactive 'r')
> (while (< (point) end))
> ...body...
> (forward-line 1)))

Just beware that as you go modify the buffer, the position that you
consider as "the end" will move as well.  You can solve this problem in
a few different ways:
- loop from end to start.
- make sure `end' is a marker rather than an integer so it will be
  automatically adjusted to keep pointing to the same logical position in
  the text.
- use narrowing (which uses similar machinery as a marker).

I personally recommend against using narrowing, unless it's *really*
much simpler.  The reason for it is that narrowing affects "everything",
so it's kind of a sledgehammer which can have unintended consequences.

> I'm wondering if there is a more straightforward way to accomplish this.

Not sure what "more straightforward" would look like.


        Stefan




  parent reply	other threads:[~2014-04-23 18:05 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-04-23 17:45 Operate on each line in region Jacob Gerlach
2014-04-23 18:03 ` Doug Lewan
2014-04-23 18:05 ` Stefan Monnier [this message]
2014-04-23 18:15 ` Pascal J. Bourguignon
     [not found] ` <mailman.20129.1398276348.10748.help-gnu-emacs@gnu.org>
2014-04-23 19:06   ` Barry Margolin
2014-04-23 19:18     ` Jacob Gerlach
2014-04-23 23:23       ` Jacob Gerlach
2014-04-23 23:44         ` Barry Margolin
2014-04-26  3:02           ` Jacob Gerlach

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