Policies/Frameworks Coding Style: Difference between revisions

From KDE Community Wiki
No edit summary
m (Remove old translation info)
(10 intermediate revisions by 3 users not shown)
Line 1: Line 1:
<languages />
 
<translate>
{{Note|1=<!--T:1-->
<!--T:1-->
This document describes the recommended coding style for KDE Frameworks. Nobody is forced to use this style, but to have consistent formatting of the source code files it is recommended to make use of it.
This document describes the recommended coding style for kdelibs. Nobody is forced to use this style, but to have consistent formatting of the source code files it is recommended to make use of it.
 


<!--T:2-->
<!--T:2-->
'''In short: Kdelibs coding style follows the [http://wiki.qt.io/Qt_Coding_Style Qt coding style], with one main difference: using curly braces even when the body of a conditional statement contains only one line.'''
'''In short: KDE Frameworks coding style follows the [http://wiki.qt.io/Qt_Coding_Style Qt coding style], with one main difference: using curly braces even when the body of a conditional statement contains only one line.'''}}


== Indentation == <!--T:3-->
== Indentation == <!--T:3-->
Line 12: Line 12:


== Variable declaration == <!--T:4-->
== Variable declaration == <!--T:4-->
* Each variable declaration on a new line
* Each variable should be declared on a new line
* Each new word in a variable name starts with a capital letter (so-called camelCase)
* Each new word in a variable name starts with a capital letter (so-called camelCase)
* Avoid abbreviations
* Avoid abbreviations
* Take useful names. No short names, except:
* Use indicative/useful names. No short names, except:
** Single character variable names can denote counters and temporary variables whose purpose is obvious
** Single character variable names can denote counters and temporary variables whose purpose is obvious
* Variables and functions start with a lowercase letter
* Variables and functions start with a lowercase letter
* Member variable names should be prefixed with '''m_''' to make it easier to distinguish them from function parameters and local variable names
** The same applies to Private (d-pointer) class member variable names,  (it may be a bit overkill when the Private class is merely used as a struct and all the code is in the public class, so you can use the '''m_''' prefix everywhere to keep it consistent, or switch to prefixing '''m_''' when adding the first ''method'' to a Private class)
* Static (global) variable names should be prefixed with '''s_'''


<!--T:5-->
<!--T:5-->
Example:
Example:
</translate>
<syntaxhighlight lang="cpp-qt">
<syntaxhighlight lang="cpp-qt">
<translate><!--T:6-->
// wrong
// wrong</translate>
KProgressBar *prbar;
KProgressBar *prbar;
QString prtxt, errstr;
QString prtxt, errstr;


<translate><!--T:7-->
// correct
// correct</translate>
KProgressBar *downloadProgressBar;
KProgressBar *downloadProgressBar;
QString progressText;
QString progressText;
QString errorString;
QString errorString;
</syntaxhighlight>
</syntaxhighlight>
<translate>


== Whitespace == <!--T:8-->
== Whitespace == <!--T:8-->
Line 46: Line 44:
<!--T:9-->
<!--T:9-->
Example:
Example:
</translate>
 
<syntaxhighlight lang="cpp-qt">
<syntaxhighlight lang="cpp-qt">
<translate><!--T:10-->
 
// wrong</translate>
// wrong
QString* myString;
QString* myString;
if(true){
if(true){
}
}


<translate><!--T:11-->
// correct
// correct</translate>
QString *myString;
QString *myString;
if (true) {
if (true) {
Line 61: Line 58:
</syntaxhighlight>
</syntaxhighlight>


<translate>
== Braces == <!--T:12-->
== Braces == <!--T:12-->
As a base rule, the left curly brace goes on the same line as the start of the statement.
As a base rule, the left curly brace goes on the same line as the start of the statement.
Line 67: Line 63:
<!--T:13-->
<!--T:13-->
Example:
Example:
</translate>
 
<syntaxhighlight lang="cpp-qt">
<syntaxhighlight lang="cpp-qt">
<translate><!--T:14-->
 
// wrong</translate>
// wrong
if (true)
if (true)
{
{
}
}


<translate><!--T:15-->
// correct
// correct</translate>
if (true) {
if (true) {
}
}
</syntaxhighlight>
</syntaxhighlight>


<translate>
 
<!--T:16-->
Exception: Function implementations, class, struct and namespace declarations always have the opening brace on the start of a line.
Exception: Function implementations, class, struct and namespace declarations always have the opening brace on the start of a line.


<!--T:17-->
Example:
Example:
</translate>
 
<syntaxhighlight lang="cpp-qt">
<syntaxhighlight lang="cpp-qt">
void debug(int i)
void debug(int i)
Line 99: Line 92:
</syntaxhighlight>
</syntaxhighlight>


<translate>
 
<!--T:18-->
<!--T:18-->
Use curly braces even when the body of a conditional statement contains only one line.
Use curly braces even when the body of a conditional statement contains only one line.
Line 105: Line 98:
<!--T:19-->
<!--T:19-->
Example:
Example:
</translate>
 
<syntaxhighlight lang="cpp-qt">
<syntaxhighlight lang="cpp-qt">
<translate><!--T:20-->
 
// wrong</translate>
// wrong
if (true)
if (true)
     return true;
     return true;
Line 115: Line 108:
     qDebug("%i", i);
     qDebug("%i", i);


<translate><!--T:21-->
 
// correct</translate>
// correct
if (true) {
if (true) {
     return true;
     return true;
Line 126: Line 119:
</syntaxhighlight>
</syntaxhighlight>


<translate>
 
== Switch statements == <!--T:22-->
== Switch statements == <!--T:22-->
Case labels are on the same column as the switch
Case labels are on the same column as the switch
Line 132: Line 125:
<!--T:23-->
<!--T:23-->
Example:
Example:
</translate>
 
<syntaxhighlight lang="cpp-qt">
<syntaxhighlight lang="cpp-qt">
switch (myEnum) {
switch (myEnum) {
Line 147: Line 140:
</syntaxhighlight>
</syntaxhighlight>


<translate>
 
== Line breaks == <!--T:24-->
== Line breaks == <!--T:24-->
Try to keep lines shorter than 100 characters, inserting line breaks as necessary.
Try to keep lines shorter than 100 characters, inserting line breaks as necessary.
Line 156: Line 149:
<!--T:26-->
<!--T:26-->
Example:
Example:
</translate>
 
<syntaxhighlight lang="cpp-qt">
<syntaxhighlight lang="cpp-qt">
<translate><!--T:27-->
 
// wrong</translate>
// wrong
#include <QtCore/QString>
#include <QtCore/QString>


<translate><!--T:28-->
 
// correct</translate>
// correct
#include <QString>
#include <QString>
</syntaxhighlight>
</syntaxhighlight>


<translate>


== Artistic Style (astyle) automatic code formatting == <!--T:29-->
== Artistic Style (astyle) automatic code formatting == <!--T:29-->
You can use [http://astyle.sourceforge.net/ astyle] (>=1.23) to format code or to test if you have followed this document. Run the following command:
You can use [http://astyle.sourceforge.net/ astyle] (>=1.23) to format code or to test if you have followed this document. Run the following command:
</translate>
 
<syntaxhighlight lang="text">
<syntaxhighlight lang="text">
astyle --indent=spaces=4 --brackets=linux \
astyle --indent=spaces=4 --brackets=linux \
Line 180: Line 172:
</syntaxhighlight>
</syntaxhighlight>


<translate>
 
<!--T:30-->
<!--T:30-->
With astyle (>=2.01) you need to run the following command:
With astyle (>=2.01) you need to run the following command:
</translate>
 
<syntaxhighlight lang="text">
<syntaxhighlight lang="text">
astyle --indent=spaces=4 --style=linux \
astyle --indent=spaces=4 --style=linux \
Line 192: Line 184:
</syntaxhighlight>
</syntaxhighlight>


<translate>
 
<!--T:31-->
<!--T:31-->
Note: With more recent astyle --brackets has become --style, so change --brackets=linux to --style=linux.
Note: With more recent astyle --brackets has become --style, so change --brackets=linux to --style=linux.
Line 200: Line 192:


<!--T:40-->
<!--T:40-->
* [https://projects.kde.org/projects/kde/kdesdk/kde-dev-scripts/repository/revisions/master/raw/astyle-kdelibs kde-dev-scripts/astyle-kdelibs] (POSIX)
* [https://commits.kde.org/kde-dev-scripts?path=astyle-kdelibs kde-dev-scripts/astyle-kdelibs] (POSIX)
* [https://projects.kde.org/projects/kde/kdesdk/kde-dev-scripts/repository/revisions/master/raw/astyle-kdelibs.bat kde-dev-scripts/astyle-kdelibs.bat] (Windows)
* [https://commits.kde.org/kde-dev-scripts?path=astyle-kdelibs.bat kde-dev-scripts/astyle-kdelibs.bat] (Windows)


== Emacs and Vim scripts == <!--T:32-->
== Emacs and Vim scripts == <!--T:32-->
Line 211: Line 203:
<!--T:33-->
<!--T:33-->
To start using kde-emacs, add the following to your .emacs:
To start using kde-emacs, add the following to your .emacs:
</translate>
 


<syntaxhighlight lang="text">
<syntaxhighlight lang="text">
Line 218: Line 210:
</syntaxhighlight>
</syntaxhighlight>


<translate>
<!--T:34-->
Many settings can be changed by editing the "kde-emacs" group via <tt>M-x customize-group</tt>.
Many settings can be changed by editing the "kde-emacs" group via <tt>M-x customize-group</tt>.


<!--T:35-->
For more information, including what the key bindings are and what additional settings you could add to your .emacs, please check <tt>kde-emacs.el</tt> itself.
For more information, including what the key bindings are and what additional settings you could add to your .emacs, please check <tt>kde-emacs.el</tt> itself.


=== Vim === <!--T:36-->
=== Vim ===
You can find a vim script in [https://projects.kde.org/projects/kde/kdesdk/kde-dev-scripts/repository/revisions/master/raw/kde-devel-vim.vim kde-devel-vim.vim] that helps you to keep the coding style correct. In addition to defaulting to the kdelibs coding style it will automatically use the correct style for Solid and kdepim code. If you want to add rules for other projects feel free to add them in the SetCodingStyle function.
You can find a vim script in [https://projects.kde.org/projects/kde/kdesdk/kde-dev-scripts/repository/revisions/master/raw/kde-devel-vim.vim kde-devel-vim.vim] that helps you to keep the coding style correct. In addition to defaulting to the KDE Frameworks coding style it will automatically use the correct style for Solid and kdepim code. If you want to add rules for other projects feel free to add them in the SetCodingStyle function.


<!--T:37-->
To use the script, include it in your {{path|~/.vimrc}} like this:
To use the script, include it in your {{path|~/.vimrc}} like this:
</translate>
 
<syntaxhighlight lang="text">
<syntaxhighlight lang="text">
source /path/to/kde/sources/kdesdk/scripts/kde-devel-vim.vim
source /path/to/kde/sources/kdesdk/scripts/kde-devel-vim.vim
</syntaxhighlight>
</syntaxhighlight>


<translate>
<!--T:38-->
Document started by Urs Wolfer. Some parts of this document have been adopted from the Qt Coding Style document posted by Zack Rusin on kde-core-devel.
Document started by Urs Wolfer. Some parts of this document have been adopted from the Qt Coding Style document posted by Zack Rusin on kde-core-devel.


<!--T:39-->
[[Category:Policies]] [[Category:C++]]
[[Category:Policies]] [[Category:C++]]
</translate>

Revision as of 16:49, 15 January 2021

Note

This document describes the recommended coding style for KDE Frameworks. Nobody is forced to use this style, but to have consistent formatting of the source code files it is recommended to make use of it.


In short: KDE Frameworks coding style follows the Qt coding style, with one main difference: using curly braces even when the body of a conditional statement contains only one line.


Indentation

  • No tabs
  • 4 Spaces instead of one tab

Variable declaration

  • Each variable should be declared on a new line
  • Each new word in a variable name starts with a capital letter (so-called camelCase)
  • Avoid abbreviations
  • Use indicative/useful names. No short names, except:
    • Single character variable names can denote counters and temporary variables whose purpose is obvious
  • Variables and functions start with a lowercase letter
  • Member variable names should be prefixed with m_ to make it easier to distinguish them from function parameters and local variable names
    • The same applies to Private (d-pointer) class member variable names, (it may be a bit overkill when the Private class is merely used as a struct and all the code is in the public class, so you can use the m_ prefix everywhere to keep it consistent, or switch to prefixing m_ when adding the first method to a Private class)
  • Static (global) variable names should be prefixed with s_

Example:

// wrong
KProgressBar *prbar;
QString prtxt, errstr;

// correct
KProgressBar *downloadProgressBar;
QString progressText;
QString errorString;

Whitespace

  • Use blank lines to group statements
  • Use only one empty line
  • Use one space after each keyword
  • For pointers or references, use a single space before '*' or '&', but not after
  • No space after a cast

Example:

// wrong
QString* myString;
if(true){
}

// correct
QString *myString;
if (true) {
}

Braces

As a base rule, the left curly brace goes on the same line as the start of the statement.

Example:

// wrong
if (true)
{
}

// correct
if (true) {
}


Exception: Function implementations, class, struct and namespace declarations always have the opening brace on the start of a line.

Example:

void debug(int i)
{
    qDebug("foo: %i", i);
}

class Debug
{
};


Use curly braces even when the body of a conditional statement contains only one line.

Example:

// wrong
if (true)
    return true;

for (int i = 0; i < 10; ++i)
    qDebug("%i", i);


// correct
if (true) {
    return true;
}

for (int i = 0; i < 10; ++i) {
    qDebug("%i", i);
}


Switch statements

Case labels are on the same column as the switch

Example:

switch (myEnum) {
case Value1:
    doSomething();
    break;
case Value2:
    doSomethingElse();
    // fall through
default:
    defaultHandling();
    break;
}


Line breaks

Try to keep lines shorter than 100 characters, inserting line breaks as necessary.

Qt Includes

  • If you add #includes for Qt classes, use only the class name.

Example:

// wrong
#include <QtCore/QString>


// correct
#include <QString>


Artistic Style (astyle) automatic code formatting

You can use astyle (>=1.23) to format code or to test if you have followed this document. Run the following command:

astyle --indent=spaces=4 --brackets=linux \
       --indent-labels --pad=oper --unpad=paren \
       --one-line=keep-statements --convert-tabs \
       --indent-preprocessor \
       `find -type f -name '*.cpp'-or -name '*.cc' -or -name '*.h'`


With astyle (>=2.01) you need to run the following command:

astyle --indent=spaces=4 --style=linux \
       --indent-labels --pad-oper --unpad-paren --pad-header \
       --keep-one-line-statements --convert-tabs \
       --indent-preprocessor \
       `find -type f -name '*.cpp' -or -name '*.cc' -or -name '*.h'`


Note: With more recent astyle --brackets has become --style, so change --brackets=linux to --style=linux.

You can find a shell script to run this command in:

Emacs and Vim scripts

The kde-dev-scripts directory in the kdesdk module contains, among other useful things, some useful additions to the Emacs and Vim text editors that make it easier to edit KDE code with them.

Emacs

The kde-emacs directory contains a set of key bindings, macros and general useful code. It is compatible with both GNU Emacs and XEmacs.

To start using kde-emacs, add the following to your .emacs:


(add-to-list 'load-path "/path/to/kde-emacs")
(require 'kde-emacs)

Many settings can be changed by editing the "kde-emacs" group via M-x customize-group.

For more information, including what the key bindings are and what additional settings you could add to your .emacs, please check kde-emacs.el itself.

Vim

You can find a vim script in kde-devel-vim.vim that helps you to keep the coding style correct. In addition to defaulting to the KDE Frameworks coding style it will automatically use the correct style for Solid and kdepim code. If you want to add rules for other projects feel free to add them in the SetCodingStyle function.

To use the script, include it in your ~/.vimrc like this:

source /path/to/kde/sources/kdesdk/scripts/kde-devel-vim.vim

Document started by Urs Wolfer. Some parts of this document have been adopted from the Qt Coding Style document posted by Zack Rusin on kde-core-devel.