bug#11266: emacs 23.4 with --batch and (next-line)

bug#11266: emacs 23.4 with --batch and (next-line)

[michael_rytting]

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I recently upgraded to emacs 23.4 and found a rather obscure bug.  When invoked with -batch emacs behaves differently with the command (next-line) compared to when it is invoked without batch.  I had to switch to using (forward-line) in my code to work around this.  This behavior can be easily seen by running.

emacs -batch config.log --eval "(next-line 1)"

And you'll see and End of buffer message.  While

emacs -Q config.log --eval "(next-line 1)"

Produces no such error.


Michael Rytting
Agilent Technologies
michael_rytting@agilent.com<mailto:michael_rytting@agilent.com>
719-590-3708


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bug#11266: emacs 23.4 with --batch and (next-line)

[Kevin Rodgers]

On 4/17/12 11:11 AM, michael_rytting@agilent.com wrote:
> I recently upgraded to emacs 23.4 and found a rather obscure bug. When invoked
> with –batch emacs behaves differently with the command (next-line) compared to
> when it is invoked without batch. I had to switch to using (forward-line) in my
> code to work around this. This behavior can be easily seen by running.
>
> emacs –batch config.log --eval "(next-line 1)"
>
> And you’ll see and End of buffer message. While
>
> emacs -Q config.log --eval "(next-line 1)"
>
> Produces no such error.

`C-h f next-line' says:

	If you are thinking of using this in a Lisp program, consider
	using `forward-line' instead.  It is usually easier to use
	and more reliable (no dependence on goal column, etc.).

And `M-: (info "(emacs)Initial Options")' reminds:

      `--batch' implies `-q' (do not load an initialization file), but
      `site-start.el' is loaded nonetheless.  It also causes Emacs to
      exit after processing all the command options.  In addition, it
      disables auto-saving except in buffers for which it has been
      explicitly requested.

-- 
Kevin Rodgers
Denver, Colorado, USA

bug#11266: emacs 23.4 with --batch and (next-line)

[Stefan Monnier]

tags 11266 notabug
thanks

> emacs -batch config.log --eval "(next-line 1)"
> And you'll see and End of buffer message.  While
> emacs -Q config.log --eval "(next-line 1)"
> Produces no such error.

`next-line' in Emacs-23 was changed to use visual lines rather than
logical lines, so its behavior depends on the shape of the selected
window.  And indeed, the selected-window depends on the terminal
(-batch uses a dummy terminal).


        Stefan

bug#11266: emacs 23.4 with --batch and (next-line)

[michael_rytting]

Good to know, I've already corrected my scripts to use forward-line instead.

-----Original Message-----
From: Stefan Monnier [mailto:monnier@IRO.UMontreal.CA] 
Sent: Wednesday, April 18, 2012 3:46 PM
To: RYTTING,MICHAEL (A-ColSprings,ex1)
Cc: 11266@debbugs.gnu.org
Subject: Re: bug#11266: emacs 23.4 with --batch and (next-line)

tags 11266 notabug
thanks

> emacs -batch config.log --eval "(next-line 1)"
> And you'll see and End of buffer message.  While emacs -Q config.log 
> --eval "(next-line 1)"
> Produces no such error.

`next-line' in Emacs-23 was changed to use visual lines rather than logical lines, so its behavior depends on the shape of the selected window.  And indeed, the selected-window depends on the terminal (-batch uses a dummy terminal).


        Stefan