Editing Vim

[http://www.vim.org/ Vim the editor] is one of the most famous text editors in the hacker programming universe. It has a plenty of extensible (script-based) capabilities and very comfortable shortcuts that makes the programmer the fastest gun of the old west. (I can imagine Vim in front of Emacs on a desert city, Vim's shot is much faster!). In this page you'll learn some tips to better adapt Vim for GNU Octave programming.

If you aren't familiar with Vim script language, you can also use [http://brainacle.com/how-to-write-vim-plugins-with-python.html Python to write Vim plugins]. If you do some for GNU Octave, please let us now.

== Vim as the default editor ==
To set Vim as the default editor launched by the GNU Octave {{Codeline|edit}} command, add one of the following line to your {{Path|~/.octaverc}} file:

 EDITOR ("gvim")

 EDITOR ("<terminal> -e 'vim'");

where {{Codeline|<terminal>}} can be [http://directory.fsf.org/wiki/Gnome-terminal gnome-terminal], [http://directory.fsf.org/wiki/Xterm xterm], or any other terminal of your preference. Please note the {{Codeline|-e}} option is common to the mentioned terminals, change it if necessary.

The {{Codeline|edit}} command defaults to asynchronous communication which creates a new process for the launched editor and then runs it in the background.  If, for some reason, you have modified this setting then you will also need to add

 edit mode async

to the {{Path|~/.octaverc}} file.

To use Vim as the default editor without starting a separate window, add the following lines to your {{Path|~/.octaverc}} file:

 edit mode sync
 edit home .
 EDITOR('vim > /dev/tty 2>&1 < /dev/tty %s')

== A better GNU Octave syntax file ==
For now, Vim does not have a dedicated, officially distributed filetype for GNU Octave. The community agreed the best solution is to use [https://www.vim.org/scripts/script.php?script_id=3600 syntax.vim] by Rik. All the instructions for installing it can be found on the hyperlink.  A companion script for indenting Octave m-files from Rik is available at [https://www.vim.org/scripts/script.php?script_id=6056 indent.vim].

== Accessing GNU Octave info ==
GNU Octave info package can be found in almost all Linux distributions.  To install the package under Ubuntu, you can type:

 $ sudo apt-get install octave<version>-info

where {{Codeline|<version>}} must be substituted by the appropriate string.

Add the following line to your {{Path|~/.vimrc}} file:

 autocmd FileType matlab setlocal keywordprg=info\ octave\ --vi-keys\ --index-search

Now, when editing a {{Path|*.m}} file, you can type {{Key|K}} in normal mode and the word under the cursor will be searched for in the GNU Octave documentation index. Pressing {{Key|,}} yields the next occurrence.

Unfortunately info does not work in dumb terminals. As gVim has only a dumb terminal, a workaround must be done to access info.  Two methods are possible.  First, one can to use a plugin, like [https://github.com/carlobaldassi/ConqueTerm ConqueTerm], which can turn a gVim buffer into a terminal emulator.
Second, one can use an external terminal emulator, preferably a fast loading one such as xterm, and install it.  To installing xterm under Ubuntu, you can type:

 $ sudo apt-get install xterm

Add the following line to your {{Path|~/.vimrc}} file:

 autocmd FileType octave setlocal keywordprg=xterm\ -e\ info\ octave\ --vi-keys\ --index-search

Now you can type {{Key|K}} in normal mode and a new terminal window will opened and the word under the cursor will be searched for in the GNU Octave documentation index.  You can set a larger font and a specific window geometry for xterm with the following line:

 autocmd FileType octave setlocal keywordprg=xterm\ -fa\ 'DejaVu\ Sans\ Mono:style=Book'\ -fs\ 12\ -geometry\ 80x50\ -e\ info\ octave\ --vi-keys\ --index-search

'''NOTE:''' If using Rik's [http://www.vim.org/scripts/script.php?script_id=3600 syntax.vim] syntax, replace {{Codeline|matlab}} by {{Codeline|octave}}.

== Jumping between control statements ==
GNU Octave has a richer set of closing tags ({{Codeline|endif}},{{Codeline|endfor}},...) but for compatibility with MATLAB most users avoid them. This sometimes makes the code hard to follow and one possible workaround is to enable the [http://www.vim.org/scripts/script.php?script_id=39 matchit.vim] plugin for jump between matching control statements. Although the plugin is distributed with Vim, it's disabled by default (see {{Codeline|:help matchit-install}}). To enable it, add the following lines to your {{Path|~/.vimrc}} file:

 set nocompatible
 filetype plugin on
 runtime macros/matchit.vim

Now that's enabled, one needs to specify the matching pairs for the GNU Octave language. The less broken solution i've found by [http://vim.1045645.n5.nabble.com/Matchit-and-identical-closing-tags-tt1145032.html#a1145034 Jake Wasserman]:

 let s:conditionalEnd = '\(([^()]*\)\@!\<end\>\([^()]*)\)\@!'
 autocmd FileType octave let b:match_words = '\<if\>\|\<while\>\|\<for\>\|\<switch\>:' .
        \ s:conditionalEnd . ',\<if\>:\<elseif\>:\<else\>:' . s:conditionalEnd

It allows to jump (quasi-)correctly even in the presence of array indexing with {{Codeline|end}}. Place the cursor on an {{Codeline|if}} keyword for example and press {{Key|%}}, it'll move to the corresponding {{Codeline|elseif}}, {{Codeline|else}}, {{Codeline|end}} keywords.

Any improvements on the {{Codeline|b:match_words}} variable are welcome.

[[Category:Editors]]