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From: "Stephen J. Turnbull" <stephen@xemacs.org>
To: "Andreas Röhler" <andreas.roehler@online.de>
Cc: Antoine Levitt <antoine.levitt@gmail.com>,
	Lennart Borgman <lennart.borgman@gmail.com>,
	Stefan Monnier <monnier@IRO.UMontreal.CA>,
	emacs-devel@gnu.org
Subject: Re: Errors in interactive commands
Date: Wed, 03 Aug 2011 16:28:31 +0900	[thread overview]
Message-ID: <87aabrhs2o.fsf@uwakimon.sk.tsukuba.ac.jp> (raw)
In-Reply-To: <4E38E70B.7030802@online.de>

Andreas Röhler writes:

 > A move-forward at the end of the buffer isn't a wrong command as such, 
 > just will not be successful.
 > 
 > Therefor it should not be raised an error, just nil returned.

This is problematic, IMO.  Suppose you have a buffer which is supposed
to have an even number of objects in it, and you want to delete every
second then.  Then

(progn
  (goto (point-min))
  (while (not (eobp))
    (forward-object 2)
    (delete-object -1)))

DTRTs, including detecting the "incorrect state" of an odd number of
objects, and not deleting the first object on an incomplete last line.

If you're going to change the behavior of the movement commands here,
I think it would be better to have them return the number of objects
left to move over.  Then 0 would mean (complete) success (how Un*x-y!)

But this would be a major change.




  reply	other threads:[~2011-08-03  7:28 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-08-02 17:46 Errors in interactive commands Antoine Levitt
2011-08-02 19:04 ` Andreas Röhler
2011-08-02 19:15 ` Lennart Borgman
2011-08-02 19:18   ` Lars Magne Ingebrigtsen
2011-08-03  7:13   ` Stephen J. Turnbull
2011-08-03  9:28     ` Lennart Borgman
2011-08-02 19:25 ` Stefan Monnier
2011-08-02 19:36   ` Lennart Borgman
2011-08-03  6:13     ` Andreas Röhler
2011-08-03  7:28       ` Stephen J. Turnbull [this message]
2011-08-03  7:46         ` Andreas Röhler
2011-08-03  8:08           ` David Kastrup
2011-08-03  8:34             ` Andreas Röhler
2011-08-03  9:09           ` Stephen J. Turnbull
2011-08-03 10:31             ` Andreas Röhler
2011-08-04  2:15               ` Stephen J. Turnbull
2011-08-03  9:37         ` Lennart Borgman
2011-08-03  9:45           ` Andreas Schwab
2011-08-03 14:41             ` Stefan Monnier
2011-08-03 15:01               ` Lennart Borgman

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