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[http://omni.isr.ist.utl.pt/~etienne/EmacsEditingOctaveCode.jpg Emacs Editing Octave Code]
[http://omni.isr.ist.utl.pt/~etienne/EmacsEditingOctaveCode.jpg Emacs Editing Octave Code]


Features & bugs:
= Emacs Octave Support =
* Highlighting of keywords and comments
* Auto-indentation
* Some annoying bugs in the above


== See also ==
The development of Octave code can greatly be facilitated using Emacs
* [http://www.gnu.org/software/octave/doc/interpreter/Emacs-Octave-Support.html Octave Manual: Appendix H Emacs Octave Support]
with Octave mode, a major mode for editing Octave files which can, for
example:
 
* automatically indent the code
* do some of the typing (with Abbrev mode)
* highlight keywords, comments, strings, etc. in different faces (with Font-lock mode on devices that support it).
 
It is also possible to run Octave from within Emacs, either by directly
entering commands at the prompt in a buffer in Inferior Octave mode, or
by interacting with Octave from within a file with Octave code.  This is
useful in particular for debugging Octave code.
 
Finally, you can convince Octave to use the Emacs info reader for
{{codeline|help -i}}.
 
All functionality is provided by the Emacs Lisp package EOS (Emacs
Octave Support).
 
Please contact [mailto:Kurt.Hornik@wu-wien.ac.at Kurt Hornik] if you have
any questions or suggestions on using EOS.
 
== Installing EOS ==
 
The Emacs package EOS consists of the three files {{Path|octave-mod.el}},
{{Path|octave-inf.el}}, and {{Path|octave-hlp.el}}.  These files,
or better yet their byte-compiled versions, should be somewhere in your Emacs
load-path.
 
If you have GNU Emacs with a version number at least as high as 19.35,
you are all set up, because EOS is respectively will be part of GNU
Emacs as of version 19.35.
 
Otherwise, copy the three files from the {{Path|emacs}} subdirectory of
the Octave distribution to a place where Emacs can find them (this
depends on how your Emacs was installed).  Byte-compile them for speed
if you want.
 
== Using Octave Mode ==
 
If you are lucky, your sysadmins have already arranged everything so
that Emacs automatically goes into Octave mode whenever you visit an
Octave code file as characterized by its extension {{Path|.m}}.
If not, proceed as follows.
 
<ol>
  <li>To begin using Octave mode for all {{Path|.m}} files you visit, add the following lines to a file loaded by Emacs at startup time, typically your {{Path|~/.emacs}} file:</li>
  <pre>
(autoload 'octave-mode "octave-mod" nil t)
(setq auto-mode-alist
      (cons '("\\.m$" . octave-mode) auto-mode-alist))
</pre>
  <li>Finally, to turn on the abbrevs, auto-fill and font-lock features automatically, also add the following lines to one of the Emacs startup files:</li>
  <pre>
(add-hook 'octave-mode-hook
          (lambda ()
            (abbrev-mode 1)
            (auto-fill-mode 1)
            (if (eq window-system 'x)
                (font-lock-mode 1))))
</pre>
</ol>
See the Emacs manual for more information about how to customize
Font-lock mode.
 
In Octave mode, the following special Emacs commands can be used in
addition to the standard Emacs commands.
 
; {{key press|C-h|m}}
: Describe the features of Octave mode.
 
; {{key press|LFD}}
: Reindent the current Octave line, insert a newline and indent the new line ({{codeline|octave-reindent-then-newline-and-indent}}).  An abbrev before point is expanded if {{codeline|abbrev-mode}} is non-{{codeline|nil}}.
 
; {{key press|TAB}}
: Indents current Octave line based on its contents and on previous lines ({codeline|indent-according-to-mode}}).
 
; {{key press|;}}
: Insert an "electric" semicolon ({codeline|octave-electric-semi}}).  If {{codeline|octave-auto-indent}} is non-{{codeline|nil}}, reindent the current line.  If {{codeline|octave-auto-newline}} is non-{{codeline|nil}}, automagically insert a newline and indent the new line.
 
; {{key press|`}}
: Start entering an abbreviation ({{codeline|octave-abbrev-start}}).  If Abbrev mode is turned on, typing {{key press|`C-h}} or {{key press|`?}} lists all abbrevs. Any other key combination is executed normally.  Note that all Octave abbrevs start with a grave accent.
 
; {{key press|M-LFD}}
: Break line at point and insert continuation marker and alignment ({{codeline|octave-split-line}}).
 
; {{key press|M-TAB}}
: Perform completion on Octave symbol preceding point, comparing that symbol against Octave's reserved words and built-in variables ({{codeline|octave-complete-symbol}}).
 
; {{key press|M-C-a}}
: Move backward to the beginning of a function ({{codeline|octave-beginning-of-defun}}). With prefix argument {{codeline|N}}, do it that many times if {codeline|N}} is positive; otherwise, move forward to the {codeline|N}}-th following beginning of a function.
 
; {{key press|M-C-e}}
: Move forward to the end of a function ({{codeline|octave-end-of-defun}}). With prefix argument {{codeline|N}}, do it that many times if {{codeline|N}} is positive; otherwise, move back to the {{codeline|N}}-th preceding end of a function.
 
; {{key press|M-C-h}}
: Puts point at beginning and mark at the end of the current Octave function, i.e., the one containing point or following point ({{codeline|octave-mark-defun}}).
 
; {{key press|M-C-q}}
: Properly indents the Octave function which contains point ({{codeline|octave-indent-defun}}).
 
; {{key press|M-;}}
: If there is no comment already on this line, create a code-level comment (started by two comment characters) if the line is empty, or an in-line comment (started by one comment character) otherwise ({{codeline|octave-indent-for-comment}}). Point is left after the start of the comment which is properly aligned.
 
; {{key press|C-c|;}}
: Puts the comment character {{codeline|#}} (more precisely, the string value of {{codeline|octave-comment-start}}) at the beginning of every line in the region ({{codeline|octave-comment-region}}).  With just {{key press|C-u}} prefix argument, uncomment each line in the region.  A numeric prefix argument {{codeline|N}} means use {{codeline|N}} comment characters.
 
; {{key press|C-c|:}}
: Uncomments every line in the region ({{codeline|octave-uncomment-region}}).
 
; {{key press|C-c|C-p}}
: Move one line of Octave code backward, skipping empty and comment lines ({{codeline|octave-previous-code-line}}).  With numeric prefix argument {{codeline|N}}, move that many code lines backward (forward if {{codeline|N}} is negative).
 
; {{key press|C-c|C-n}}
: Move one line of Octave code forward, skipping empty and comment lines ({{codeline|octave-next-code-line}}).  With numeric prefix argument {{codeline|N}}, move that many code lines forward (backward if {{codeline|N}} is negative).
 
; {{key press|C-c|C-a}}
: Move to the `real' beginning of the current line
({{codeline|octave-beginning-of-line}}).  If point is in an empty or comment line, simply go to its beginning; otherwise, move backwards to the beginning of the first code line which is not inside a continuation statement, i.e., which does not follow a code line ending in {{codeline|...}} or {{codeline|\}}, or is inside an open parenthesis list.
 
; {{key press|C-c|C-e}}
: Move to the `real' end of the current line ({{codeline|octave-end-of-line}}). If point is in a code line, move forward to the end of the first Octave code line which does not end in {{codeline|...}} or {{codeline|\}} or is inside an open parenthesis list.  Otherwise, simply go to the end of the current line.
 
; {{key press|C-c|M-C-n}}
: Move forward across one balanced begin-end block of Octave code ({{codeline|octave-forward-block}}).  With numeric prefix argument {{codeline|N}}, move forward across {{codeline|n}} such blocks (backward if {{codeline|N}} is negative).
 
; {{key press|C-c|M-C-p}}
: Move back across one balanced begin-end block of Octave code ({{codeline|octave-backward-block}}).  With numeric prefix argument {{codeline|N}}, move backward across {{codeline|N}} such blocks (forward if {{codeline|N}} is negative).
 
; {{key press|C-c|M-C-d}}
: Move forward down one begin-end block level of Octave code ({{codeline|octave-down-block}}).  With numeric prefix argument, do it that many times; a negative argument means move backward, but still go down one level.
 
; {{key press|C-c|M-C-u}}
: Move backward out of one begin-end block level of Octave code ({{codeline|octave-backward-up-block}}).  With numeric prefix argument, do it that many times; a negative argument means move forward, but still to a less deep spot.
 
; {{key press|C-c|M-C-h}}
: Put point at the beginning of this block, mark at the end ({{codeline|octave-mark-block}}). The block marked is the one that contains point or follows point.
 
; {{key press|C-c|]}}
: Close the current block on a separate line ({{codeline|octave-close-block}}). An error is signaled if no block to close is found.
 
; {{key press|C-c|f}}
: Insert a function skeleton, prompting for the function's name, arguments and return values which have to be entered without parentheses ({{codeline|octave-insert-defun}}).
 
; {{key press|C-c|C-h}}
: Search the function, operator and variable indices of all info files with documentation for Octave for entries ({{codeline|octave-help}}).  If used interactively, the entry is prompted for with completion.  If multiple matches are found, one can cycle through them using the standard {{codeline|,}} ({{codeline|Info-index-next}}) command of the Info reader.
:
: The variable {{codeline|octave-help-files}} is a list of files to search through and defaults to {{codeline|'("octave")}}.  If there is also an Octave Local Guide with corresponding info file, say, {{Path|octave-LG}}, you can have {{codeline|octave-help}} search both files by {{codeline|(setq octave-help-files '("octave" "octave-LG"))}} in one of your Emacs startup files.
 
A common problem is that the {{key press|RET}} key does ''not'' indent the
line to where the new text should go after inserting the newline.  This
is because the standard Emacs convention is that {{key press|RET}} (aka
{{key press|C-m}}) just adds a newline, whereas {{key press|LFD}} (aka {{key press|C-j}}) adds a
newline and indents it.  This is particularly inconvenient for users with
keyboards which do not have a special {{key press|LFD}} key at all; in such
cases, it is typically more convenient to use {{key press|RET}} as the {{key press|LFD}}
key (rather than typing {{key press|C-j}}).
 
You can make {{key press|RET}} do this by adding
 
<pre>
(define-key octave-mode-map "\C-m"
  'octave-reindent-then-newline-and-indent)
</pre>
 
to one of your Emacs startup files.  Another, more generally applicable
solution is
 
<pre>
(defun RET-behaves-as-LFD ()
  (let ((x (key-binding "\C-j")))
    (local-set-key "\C-m" x)))
(add-hook 'octave-mode-hook 'RET-behaves-as-LFD)
</pre>
 
(this works for all modes by adding to the startup hooks, without having
to know the particular binding of {{key press|RET}} in that mode!).  Similar
considerations apply for using {{key press|M-RET}} as {{key press|M-LFD}}.  As
[mailto:bwarsaw@cnri.reston.va.us Barry A. Warsaw] says in the documentation for his
{{codeline|cc-mode}}, "This is a very common question. :-) If you want
this to be the default behavior, don't lobby me, lobby RMS!"
 
The following variables can be used to customize Octave mode.
 
; {{codeline|octave-auto-indent}}
: Non-{{codeline|nil}} means auto-indent the current line after a semicolon or space.  Default is {{codeline|nil}}.
 
; {{codeline|octave-auto-newline}}
: Non-{{codeline|nil}} means auto-insert a newline and indent after semicolons are typed.  The default value is {{codeline|nil}}.
 
; {{codeline|octave-blink-matching-block}}
: Non-{{codeline|nil}} means show matching begin of block when inserting a space, newline or {{codeline|;}} after an else or end keyword.  Default is {{codeline|t}}. This is an extremely useful feature for automatically verifying that the keywords match --- if they don't, an error message is displayed.
 
; {{codeline|octave-block-offset}}
: Extra indentation applied to statements in block structures. Default is 2.
 
; {{codeline|octave-continuation-offset}}
: Extra indentation applied to Octave continuation lines. Default is 4.
 
; {{codeline|octave-continuation-string}}
: String used for Octave continuation lines. Normally {{codeline|\}}.
 
; {{codeline|octave-mode-startup-message}}
: If {{codeline|t}} (default), a startup message is displayed when Octave mode is called.
 
If Font Lock mode is enabled, Octave mode will display
 
* strings in {{codeline|font-lock-string-face}}
 
* comments in {{codeline|font-lock-comment-face}}
 
* the Octave reserved words (such as all block keywords) and the text functions (such as {{codeline|cd}} or {{codeline|who}}) which are also reserved using {{codeline|font-lock-keyword-face}}
 
* the built-in operators ({{codeline|&&}}, {{codeline|<nowiki>==</nowiki>}}, {{codeline|...}}) using {{codeline|font-lock-reference-face}}
 
* and the function names in function declarations in {{codeline|font-lock-function-name-face}}.
 
There is also rudimentary support for Imenu (currently, function
names can be indexed).
 
You can generate {{Path|TAGS}} files for Emacs from Octave {{Path|.m}} files using
the shell script {{codeline|octave-tags}} that is installed alongside your copy of
Octave.
 
Customization of Octave mode can be performed by modification of the
variable {{codeline|octave-mode-hook}}.  If the value of this variable is
non-{{codeline|nil}}, turning on Octave mode calls its value.
 
If you discover a problem with Octave mode, you can conveniently send a
bug report using {{key press|C-c|C-b}} ({{codeline|octave-submit-bug-report}}).  This
automatically sets up a mail buffer with version information already
added.  You just need to add a description of the problem, including a
reproducible test case and send the message.
 
== Running Octave from Within Emacs ==
 
The package octave provides commands for running an inferior
Octave process in a special Emacs buffer.  Use
{{key press|M-x}} {{codeline|run-octave}}
to directly start an inferior Octave process.  If Emacs does not know
about this command, add the line
{{codeline|(autoload 'run-octave "octave-inf" nil t)}}
to your {{Path|.emacs}} file.
 
This will start Octave in a special buffer the name of which is
specified by the variable {{codeline|inferior-octave-buffer}} and defaults to
"*Inferior Octave*".  From within this buffer, you can
interact with the inferior Octave process as usual, i.e., by entering
Octave commands at the prompt.  The buffer is in Inferior Octave mode,
which is derived from the standard Comint mode, a major mode for
interacting with an inferior interpreter.  See the documentation for
{{codeline|comint-mode}} for more details, and use {{key press|C-h|b}} to find out
about available special keybindings.
 
You can also communicate with an inferior Octave process from within
files with Octave code (i.e., buffers in Octave mode), using the
following commands.
 
; {{key press|C-c|i|l}}
: Send the current line to the inferior Octave process ({{codeline|octave-send-line}}). With positive prefix argument {{codeline|N}}, send that many lines. If {{codeline|octave-send-line-auto-forward}} is non-{{codeline|nil}}, go to the next unsent code line.
 
; {{key press|C-c|i|b}}
: Send the current block to the inferior Octave process ({{codeline|octave-send-block}}).
 
; {{key press|C-c|i|f}}
: Send the current function to the inferior Octave process ({{codeline|octave-send-defun}}).
 
; {{key press|C-c|i|r}}
: Send the region to the inferior Octave process ({{codeline|octave-send-region}}).
 
; {{key press|C-c|i|s}}
: Make sure that `inferior-octave-buffer' is displayed ({{codeline|octave-show-process-buffer}}).
 
; {{key press|C-c|i|h}}
: Delete all windows that display the inferior Octave buffer ({{codeline|octave-hide-process-buffer}}).
 
; {{key press|C-c|i|k}}
: Kill the inferior Octave process and its buffer ({{codeline|octave-kill-process}}).
 
The effect of the commands which send code to the Octave process can be
customized by the following variables.
 
; {{codeline|octave-send-echo-input}}
: Non-{{codeline|nil}} means echo input sent to the inferior Octave process. Default is {{codeline|t}}.
 
; {{codeline|octave-send-show-buffer}}
Non-{{codeline|nil}} means display the buffer running the Octave process after sending a command (but without selecting it). Default is {{codeline|t}}.
 
If you send code and there is no inferior Octave process yet, it will be
started automatically.
 
The startup of the inferior Octave process is highly customizable.
The variable {{codeline|inferior-octave-startup-args}} can be used for
specifying command lines arguments to be passed to Octave on startup
as a list of strings.  For example, to suppress the startup message and
use traditional mode, set this to {{codeline|'("-q" "--traditional")}}.
You can also specify a startup file of Octave commands to be loaded on
startup; note that these commands will not produce any visible output
in the process buffer.  Which file to use is controlled by the variable
{{codeline|inferior-octave-startup-file}}.  If this is {{codeline|nil}}, the file
{{Path|~/.emacs-octave}} is used if it exists.
 
And finally, {{codeline|inferior-octave-mode-hook}} is run after starting the
process and putting its buffer into Inferior Octave mode.  Hence, if you
like the up and down arrow keys to behave in the interaction buffer as
in the shell, and you want this buffer to use nice colors, add
 
<pre>
(add-hook 'inferior-octave-mode-hook
          (lambda ()
            (turn-on-font-lock)
            (define-key inferior-octave-mode-map [up]
              'comint-previous-input)
            (define-key inferior-octave-mode-map [down]
              'comint-next-input)))
</pre>
 
to your {{Path|.emacs}} file.  You could also swap the roles of {{key press|C-a}}
({{codeline|beginning-of-line}}) and {{key press|C-c|C-a}} ({{codeline|comint-bol}}) using
this hook.
 
Note that if you set your Octave prompts to something different
from the defaults, make sure that {{codeline|inferior-octave-prompt}} matches
them.  Otherwise, ''nothing'' will work, because Emacs will not know
when Octave is waiting for input, or done sending output.
 
== Using the Emacs Info Reader for Octave ==
 
You may also use the Emacs Info reader with Octave's {{codeline|doc}} function.
For this, the package gnuserv needs to be installed.
 
If gnuserv is installed, add the lines
 
<pre>
(autoload 'octave-help "octave-hlp" nil t)
(require 'gnuserv)
(gnuserv-start)
</pre>
 
to your {{Path|.emacs}} file.
 
You can use either plain Emacs Info or the function {{codeline|octave-help}}
as your Octave info reader (for {{codeline|help -i}}).  In the former case,
use {{codeline|info_program ("info-emacs-info")}}.
The latter is perhaps more attractive because it allows one to look up keys
in the indices of several info files related to Octave (provided
that the Emacs variable {{codeline|octave-help-files}} is set correctly).  In
this case, use {{codeline|info_program ("info-emacs-octave-help")}}.
 
If you use Octave from within Emacs, it is best to add these settings to
your {{Path|~/.emacs-octave}} startup file (or the file pointed to by the
Emacs variable {{codeline|inferior-octave-startup-file}}).


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