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Coding and Documentation Style

Error Logging
GPL header
Git change log
Source Code Style
Shell Script Style
External Software Tools
Geeqie Software Tools
Documentation
Documentation - C code
Documentation - Script files
Documentation - Markdown
Doxygen

Error Logging

DEBUG_0()

Use DEBUG_0() only for temporary debugging i.e. not in code in the repository. The user will then not see irrelevant debug output when the default debug level = 0 is used.

log_printf()

If the first word of the message is "error" or "warning" (case insensitive) the message will be color-coded appropriately.

  • Note that these messages are output in the idle loop.

print_term()

print_term(gboolean err, const gchar *text_utf8)

  • If err is TRUE output is to STDERR, otherwise to STDOUT

DEBUG_NAME(widget)

For use with the GTKInspector to provide a visual indication of where objects are declared.

Sample command line call:
GTK_DEBUG=interactive src/geeqie

GPL header

Include a header in every file, like this:

/*
 * Copyright (C) <year> The Geeqie Team
 *
 * Author: Author1  
 * Author: Author2  
 *  
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 *
 * Optional description of purpose of file.
 *
*/

git change-log

If referencing a Geeqie GitHub issue, include the issue number in the summary line and a hyperlink to the GitHub issue webpage in the message body. Start with a short summary in the first line (without a dot at the end) followed by a empty line.

Use whole sentences beginning with Capital letter. For each modification use a new line. Or you can write the theme, colon and then every change on new line, begin with "- ".

See also A Note About Git Commit Messages

Example:

I did some bugfixes

There was the bug that something was wrong. I fixed it.

Library:
- the interface was modified
- new functions were added`

Also please use your full name and a working e-mail address as author for any contribution.

Source Code Style

Indentation: tabs at 4 spaces

Names:

  • of variables & functions: small_letters
  • of defines: CAPITAL_LETTERS

Try to use explicit variable and function names.
Try not to use macros.
Use either "struct foo" OR "foo"; never both

Conditions, cycles:

if (<cond>)
    {
    <command>;
    ...
    <command>;
    }
else
    {
    <command>;
    ...
    <command>;
    }

if (<cond_very_very_very_very_very_very_very_very_very_long> &&
<cond2very_very_very_very_very_very_very_very_very_long>)
<the_only_command>;

switch (<var>)
    {
    case 0:
        <command>;
        <command>;
        break;
    case 1:
        <command>; break;
    }

for (i = 0; i <= 10; i++)
    {
    <command>;
    ...
    <command>;
    }

Functions:

gint bar(<var_def>, <var_def>, <var_def>)
{
    <command>;
    ...
    <command>;

    return 0; // i.e. SUCCESS; if error, you must return minus <err_no> @FIXME
}

void bar2(void)
{
    <command>;
    ...
    <command>;
}

Pragma: (Indentation 2 spaces)

#ifdef ENABLE_NLS
#  undef _
#  define _(String) (String)
#endif /* ENABLE_NLS */

Headers:

#ifndef _FILENAME_H

Use spaces around every operator (except ., ->, ++ and --).
Unary operator * and & are missing the space from right, (and also unary -).

As you can see above, parentheses are closed to inside, i.e. (blah blah)
In function(<var>) there is no space before the (.
You may use more tabs/spaces than you ought to (according to this CodingStyle), if it makes your code nicer in being vertically indented.
Variables declarations should be followed by a blank line and should always be at the start of the block.

Use glib types when possible (ie. gint and gchar instead of int and char).
Use glib functions when possible (i.e. g_ascii_isspace() instead of isspace()).
Check if used functions are not deprecated.
Use UNUSED() for unused function parameters.

Shell Script Style

Use /bin/sh as the interpreter directive.
Ensure the script is POSIX compliant.
Use printf rather than echo except for plain text.
There are several versions of mktemp. Using the following definition helps portability (note that template is not optional):

mktemp [-d] [-q] template ...

and use for example this style:

mktemp  "${TMPDIR:-/tmp}/geeqie.XXXXXXXXXX"

External Software Tools

astyle

There is no code format program that exactly matches the above style, but if you are writing new code the following command line program formats code to a fairly close level:

astyle --options=<options file>

Where the options file might contain:

style=vtk
indent=force-tab
pad-oper
pad-header
unpad-paren
align-pointer=name
align-reference=name

cppcheck

A lint-style program may be used, e.g.

cppcheck --language=c --library=gtk --enable=all --force  -USA_SIGINFO -UZD_EXPORT -Ugettext_noop -DG_KEY_FILE_DESKTOP_GROUP --template=gcc -I .. --quiet --suppressions-list=<suppressions file>

Where the suppressions file might contain:

missingIncludeSystem
variableScope
unusedFunction
unmatchedSuppression

markdownlint

Markdown documents may be validated with e.g. markdownlint.

mdl --style <style file>`

Where the style file might contain:

all
rule 'MD007', :indent => 4
rule 'MD009', :br_spaces => 2
rule 'MD010', :code_blocks => true
exclude_rule 'MD013'

shellcheck

Shell scripts may also be validated, e.g.

shellcheck --enable=add-default-case,avoid-nullary-conditions,check-unassigned-uppercase,deprecate-which,quote-safe-variables

shfmt

Shell scripts may formatted to some extent with shfmt. At the time of writing it does not format if, for or while statements in the style used by Geeqie.
However the following script can be used to achieve that:

#!/bin/sh

shfmt -s -p -ci -sr -fn | awk '
    {if ($0 ~ /; then/)
        {
        match($0, /^\t*/);
        printf('%s\n', substr($0, 0, length($0) - 6));
        printf('%s, substr("\t\t\t\t\t\t\t\t\t\t", 1, RLENGTH))
        print("then")
        }
    else if ($0 ~ /; do/)
        {
        match($0, /^\t*/);
        printf('%s\n', substr($0, 0, length($0) - 4));
        printf('%s', substr("\t\t\t\t\t\t\t\t\t\t", 1, RLENGTH))
        print("do")
        }
    else
        {
        print
        }
    }'

xmllint

The .xml Help files may be validated with e.g. xmllint.

Geeqie Software Tools

See the shell scripts section in the Doxygen documentation (File List, detail level 3, except the src sublist).

Documentation

Use American, rather than British English, spelling. This will facilitate consistent text searches. User text may be translated via the en_GB.po file.

To document the code use the following rules to allow extraction with Doxygen.
Not all comments have to be Doxygen comments.

C code

  • Use C comments in plain C files and use C++ comments in C++ files for one line comments.
  • Use /** (note the two asterisks) to start comments to be extracted by Doxygen and start every following line with * as shown below.
  • Use @ to indicate Doxygen keywords/commands (see below).
  • Use the @deprecated command to indicate the function is subject to be deleted or to a complete rewrite.

To document functions or big structures:

/**
 * @brief This is a short description of the function.
 *
 * This function does ...
 *
 * @param x1 This is the first parameter named x1
 * @param y1 This is the second parameter named y1
 * @return What the function returns
 *    You can extend that return description (or anything else) by indenting the
 *    following lines until the next empty line or the next keyword/command.
 * @see Cross reference
 */

To document members of a structure that have to be documented (use it at least for big structures) use the /**< format:

gint counter; /**< This counter counts images */

Document TODO or FIXME comments as:

/**  
* @todo

or

/**  
* @FIXME

Script files

Script files such as .sh, .pl, and .awk should have the file relevant file extension or be symlinked as so.

Doxygen comments should start each line with ##, and each file should contain:

## @file
## @brief <one line description>
## <contents description>
##

Markdown

For a newline use two spaces (a backslash is not interpreted correctly by Doxygen).

Doxygen

For further documentation about Doxygen see the Doxygen Manual.
For the possible commands you may use, see Doxygen Special Commands.

The file ./scripts/doxygen-help.sh may be used to integrate access to the Doxygen files into a code editor.

The following environment variables may be set to personalize the Doxygen output:

DOCDIR=<output folder>
SRCDIR=<the top level directory of the project>
PROJECT=
VERSION=
PLANTUML_JAR_PATH=
INLINE_SOURCES=<YES|NO>
STRIP_CODE_COMMENTS=<YES|NO>

Ref: INLINE_SOURCES
Ref: STRIP_CODE_COMMENTS

For shell scripts to be documented, the file doxygen-bash.sed must be in the $PATH environment variable.
It can be download from here:

wget https://raw.githubusercontent.com/Anvil/bash-doxygen/master/doxygen-bash.sed
chmod +x doxygen-bash.sed

To include diagrams in the Doxygen output, the following are required to be installed. The installation process will vary between distributions:

The PlantUML jar

sudo apt install default-jre
sudo apt install texlive-font-utils

But in case just think about that the documentation is for other developers not for the end user. So keep the focus.