Editing Project - Documentation

:''This article contains project ideas related to improve GNU Octave's documentation.  For general project ideas, see [[Projects]].''

== News ==

[[File:SeasonofDocs Logo SecondaryGrey 300ppi.png|right|200px|link=https://g.co/seasonofdocs]]
* GNU Octave might apply for [https://g.co/seasonofdocs Google Season of Docs (GSoD)] in 2022.  Examples of successful projects from other organizations can be found at:
** latest: [https://developers.google.com/season-of-docs/docs/participants GSoD Current Participants List]
** 2020: [https://developers.google.com/season-of-docs/docs/2020/participants GSOD 2020 Participants Archive]

* Discuss about your ideas and application with us by:
** [https://octave.discourse.group/ GNU Octave User and Developer Forum]
** [[IRC]]
** updating this wiki page

== Existing Documentation ==
:''For a comprehensive list see [[Publications about Octave]].''

* [https://www.gnu.org/software/texinfo/ Texinfo] user / developer documentation for the [https://octave.org/doc/interpreter/ Octave interpreter].

* [[Doxygen]] documentation for the internal C++ classes and external API.

* This wiki:
** [[FAQ]]
** [[:Category:Resources | Resources: Tutorials, Examples, Tips and Tricks, ...]]

== Suggested Projects ==

=== Octave's interpreter documentation ===

'''Description'''

The documentation for the interpreter is presumably the oldest, long grown documentation of the GNU Octave project.  It is mostly written in [https://www.gnu.org/software/texinfo/ Texinfo] and strongly interleaved in the [[Building | Octave build process]], i.e., it is necessary to build Octave from source to generate included figures.  Additionally, large portions of the Texinfo source are auto generated to stay close to the source code and to avoid stale documentation.  A special type of this auto generation are the so-called [[Help text | "docstrings"]], which are extracted from both C++ files and Octave's own script files (m-files). 

The resulting Texinfo sources are translated to Info, PDF, PostScript, and HTML, whereas the HTML is further processed to match the [https://doc.qt.io/qt-5/qthelp-framework.html QT Help Framework], which is displayed in the Octave GUI.

'''Improvements'''

* Easy but long task: Every function description should mention the output variable if there is one. See bug {{bug|61681}} and [[#Working list of functions needing output variables]] below.
* Check for inconsistencies in the manual, e.g., outdated descriptions, awkwardly ordered information, ...
* More examples and demo files for using each Octave command.
* More figures to demonstrate Octave's plotting capabilities, but regard doc size and building time.
* Think about a superior organization/splitting of the manual.  Currently it covers many topics interleaved: user manual, function reference, developer guide.
** Idea for a function reference including [[Octave Forge]] packages: https://octave.sourceforge.io/docs.php (unmaintained)
* Document the documentation building process (e.g. rename and document involved scripts).

'''Long term goals / highly controversial within the community'''

* Syntax, structure, and source-code readability of Texinfo is a burden for some developers and newcomers.  In short it is no "fun" editing those.  Consider replacement by
** [https://commonmark.org/ CommonMark/Markdown]
** [https://docutils.readthedocs.io/en/sphinx-docs/user/rst/quickstart.html reStructuredText] / [https://www.sphinx-doc.org/ Sphinx]
** ...

'''Resources'''

* '''Style Guides'''
: [[Contribution guidelines#Coding style]]
* '''Source code'''
: https://hg.savannah.gnu.org/hgweb/octave/file/tip/doc/interpreter
* '''Required skills'''
: [https://www.gnu.org/software/texinfo/ Texinfo], [https://www.mercurial-scm.org/ hg], [[Building | building Octave from source]]
* '''Potential mentors'''
: [[User:siko1056 | Kai]]

=== Octave's internal documentation ===

'''Description'''

[https://hg.savannah.gnu.org/hgweb/octave/rev/e16080e36cf9 Since 2013], Octave makes use of [http://www.doxygen.nl/ Doxygen], and [https://hg.savannah.gnu.org/hgweb/octave/file/tip/etc/HACKING.md <code>etc/HACKING.md</code>] for its internal documentation.  There has been only moderate effort to add Doxygen comments to the entire code base or to create verbose descriptions for key techniques about how Octave works (here an example for [https://octave.org/doxygen/5.2/df/d4d/Macros.html important Octave macros]).  Potential reasons for this circumstance are:
# Lack of developer knowledge (code grew over 25 years), many "cryptic" macros, very complex class inheritance trees:
#* [https://octave.org/doxygen/5.2/d0/d26/classArray.html <code>liboctave/Array</code>]
#* [https://octave.org/doxygen/5.2/d6/d68/classoctave__base__value.html <code>libinterp/octave_base_value</code>]
# long Doxygen build time to see results of documentation effort
# huge size (about 2 GB), very impractical to "carry around", [https://octave.org/doxygen] slowly responding

Nevertheless, there is a need for internal documentation:
# Comprehensive documentation of Octave's [https://octave.org/doc/v5.2.0/External-Code-Interface.html external code interface].
# Enable newcomers (e.g. GSoC students) to study Octave's code easily.
# Avoid knowledge drain ([https://en.wikipedia.org/wiki/Bus_factor bus factor]).

'''Improvements'''

* The internal documentation should cover the following topics (a more verbose extension of [https://hg.savannah.gnu.org/hgweb/octave/file/tip/etc/HACKING.md <code>etc/HACKING.md</code>] [https://octave.org/doxygen/5.2/d1/d10/Hacking.html (html)]):
** Overview about the code base (liboctave, libinterp, libgui, ...).
** How Octave is built (necessary tools [versions], involved scripts, ...).
** The release procedure, e.g. [[6.1 Release Checklist]].
* Make the internal documentation '''obvious, easy to study and to extend, avoid effort duplication'''.
** The internal documentation should not be fixed on Doxygen comments only.
** As Octave's GUI makes use of qt, Doxygen might also be replaced by [https://doc.qt.io/qt-5/qdoc-index.html QDoc] with comparable markup.
** Splitting the documentation into a wiki portion, etc., is imaginable, but it must be clearly documented where to find which information, '''avoid duplication''', nobody wants to update information in more than one location.
* Technical goals are:
** Smaller memory footprint for individual documents (unlike current Doxygen with about 2 GB).
** Fast build time.
** Lightweight (existing) documentation system. No heavy preprocessing / code generation by custom scripts.
** As close to the source as necessary.  Make it difficult to update the code while not updating its documentation.  E.g. no wiki documentation for Octave's C++ files.

'''Resources'''

* '''Style Guides'''
: [[C++ style guide#Doxygen]]
* '''Source code'''
: https://hg.savannah.gnu.org/hgweb/octave/file/tip/doc/doxyhtml
* '''Required skills'''
: [http://www.doxygen.nl/ Doxygen], [https://www.mercurial-scm.org/ hg], [[Building | building Octave from source]]
* '''Potential mentors'''
: [[User:siko1056 | Kai]]

==Appendix==
[[Category:Project Ideas]]