linefeed ^L symbol

linefeed ^L symbol

[Tyler Smith]

Hi,

I've just reinstalled Emacs 22.1 from source on Debian Lenny. I notice
now that ^L shows up here and there, presumably where a newline should
be. Does this mean I've messed something up something in the config? I
shouldn't be seeing escape characters like this should I?

Examples:
From the Paragraph Start customize variable window:
Paragraph Start: Hide Value \f\|[ 	]*$\|.* wrote:$\|.* wrote:$

The actual value of this variable is:
"\f\\|[ 	]*$\\|.* wrote:$\\|.* wrote:$\\|.* wrote:$\\|.* wrote:$"

I'm also confused as to why I should have \f in there to begin with,
since I think Unix-like systems use \n instead?

Thanks for any clarification,

Tyler

Re: linefeed ^L symbol

[Peter Dyballa]

Am 11.12.2007 um 17:41 schrieb Tyler Smith:

> I notice
> now that ^L shows up here and there, presumably where a newline should
> be.

^L is a page feed/newpage. Sometimes they're there on purpose. See  
also: man ascii.

--
Greetings

   Pete

Clovis' Consideration of an Atmospheric Anomaly:
         The perversity of nature is nowhere better demonstrated
         than by the fact that, when exposed to the same atmosphere,
         bread becomes hard while crackers become soft.

Re: linefeed ^L symbol

[Xah Lee]

Tyler Smith:
<<I've just reinstalled Emacs 22.1 from source on Debian Lenny. I
notice now that ^L shows up here and there, presumably where a newline
should be.>>

The "^L" char is form feed (ascii 12). It is not the unix newline char
(which is line feed, ^J, ascii 10).

During the 1980s or early 1990s, the form feed char basically
functions as page break marker. It is still what emacs uses it for.

However, after 2 decades of computing industry changes, using the form
feed char for page break in source code is no longer widely practiced.
Emacs still uses it so because emacs did not take particular effort to
modernize. (modernize here means to adopt changing situation (usually
for the better), as opposed to following fashions and trends)

In emacs, you can jump to next ^L by pressing "Ctrl+x ]" and previosu
by "Ctrl+x [". By tradition, elisp code still uses it to indicate a
code page break. (not sure if this is mentioned or recommended in
emacs coding style guide, or how frequent it is used in existing elisp
files)

For more detail on this, please see:

* Why Emacs's Keyboard Shortcuts Are Painful
http://xahlee.org/emacs/emacs_kb_shortcuts_pain.html

* The Confusion of Emacs's Keystroke Representation
http://xahlee.org/emacs/keystroke_rep.html

  Xah
  xah@xahlee.org
\xAD\xF4 http://xahlee.org/

On Dec 11, 8:41 am, Tyler Smith <tyler.sm...@mail.mcgill.ca> wrote:
> Hi,
>
> I've just reinstalled Emacs 22.1 from source on Debian Lenny. I notice
> now that ^L shows up here and there, presumably where a newline should
> be. Does this mean I've messed something up something in the config? I
> shouldn't be seeing escape characters like this should I?
>
> Examples:
> From the Paragraph Start customize variable window:
> Paragraph Start: Hide Value  \|[        ]*$\|.* wrote:$\|.* wrote:$
>
> The actual value of this variable is:
> "\f\\|[    ]*$\\|.* wrote:$\\|.* wrote:$\\|.* wrote:$\\|.* wrote:$"
>
> I'm also confused as to why I should have \f in there to begin with,
> since I think Unix-like systems use \n instead?
>
> Thanks for any clarification,
>
> Tyler

Re: linefeed ^L symbol

[Giorgos Keramidas]

On 11 Dec 2007 16:41:56 GMT, Tyler Smith <tyler.smith@mail.mcgill.ca> wrote:
> Hi,
>
> I've just reinstalled Emacs 22.1 from source on Debian Lenny. I notice
> now that ^L shows up here and there, presumably where a newline should
> be. Does this mean I've messed something up something in the config? I
> shouldn't be seeing escape characters like this should I?
>
> Examples:
> From the Paragraph Start customize variable window:
> Paragraph Start: Hide Value \f\|[ 	]*$\|.* wrote:$\|.* wrote:$
>
> The actual value of this variable is:
> "\f\\|[ 	]*$\\|.* wrote:$\\|.* wrote:$\\|.* wrote:$\\|.* wrote:$"
>
> I'm also confused as to why I should have \f in there to begin with,
> since I think Unix-like systems use \n instead?

You are a bit confused.  ^L is not `line feed', but a different
character (with ASCII code 12 instead of 10).  It is commonly
represented by the C-like escape sequence "\f" in strings...

To see more information about the ^L character, type in a scratch buffer
the following:

    C-q C-l

Then move the point to that character and type `C-u C-x =' :)