Programming guidelines

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NAVIT is a team-project, thus a lot of coders are working on it's development and codebase. To get a unified coding style and make it easier for everybody to work with parts, that someone else wrote, we tried to specify the formating of our source and how we deal with third party modules as following.

Coding Style

  • Intention with tabs
  • 8 characters per tab
  • K&R style
  • Function name at line start

indent usage:

    indent --procnames-start-lines --k-and-r-style --indent-level 8

Character encoding and line breaks

All non-ascii-strings must be utf-8 encoded. Line breaks consist of a linefeed (no carriage return)

C Standard

C95. That means:

  • No inline declarations of variables

Instead of

 {
    do_something();
    int a=do_something_else();
 }

use

 {
    int a;
    do_something();
    a=do_something_else();
 }
  • No dynamic arrays

Instead of

 void
 myfunc(int count)
 {
    struct mystruct x[count]
 }

use

 void
 myfunc(int count)
 {
    struct mystruct *x=g_alloca(count*sizeof(struct mystruct));
 }
  • No empty initializers

Instead of

 struct mystruct m={};

use

 struct mystruct m={0,};
  • Use /* and */ for comments instead of //

Note: The restriction to C95 exists mainly to help the WinCE port, which uses a compiler without full support for C99. Once all platforms supported by Navit use a compiler capable of C99, this decision may be reconsidered.

Use of libraries

  • Navit uses GLib extensively. In general, code should use GLib's functions in preference to functions from libc. For example, use g_new() / g_free(), rather than malloc() / free(), g_strcmp0() rather than strcmp() etc.
  • Unfortunately, not all platforms that Navit runs on have a native GLib version. For these platforms, there is code replacing these libraries under navit/support/. Take care to only use functions from GLib (or other libraries), that is also present under navit/support/. If you need something that is not present there, please discuss it on IRC - it may be possible to add it to the support code.

Comments

General guidelines

  • Comments for the entire file and classes/structs/methods/functions is the minimum requirement. Examples see below.
  • Please comment your code in a significant and reasonable way.
  • A quick description of (complicated) algorithms makes it easier for other developers and helps them to save a lot of time.
  • Please add a doxygen description for all function you should add. You are we1come to add it too to older functions. Doxygen result can be found there : http://doxygen.navit-project.org

Example :

 /**
 * @brief Change the current zoom level, zooming closer to the ground.
 *
 * This sentence starts the "detailed" description (because this is a new
 * paragraph).
 *
 * @param navit The navit instance
 * @param factor The zoom factor, usually 2
 * @param p The invariant point (if set to NULL, default to center)
 * @returns nothing
 */
 void
 navit_zoom_in(struct navit *this_, int factor, struct point *p)

Templates

This is an example how you could (should) comment your files and functions. If you have any suggestions for improvement, please feel free to discuss them with us. These templates should be doxygen-conform - if not, please correct them. A more comprehensive overview of possible documentation can be found here.

Files

/** @file can.cpp
 * @brief CAN-Camera Framework :: CAN container class and high level functions
 * 
 * Some documentation regarding this file.
 *
 * @Author Stefan Klumpp <sk@....> 
 * @date 2008
 */
<include "can.h">
.
.
.

Classes/Structs/Functions/Methods

/** 
 * @brief A short description of this function
 *
 * A lot more of documentation regarding this function.
 * @param raw_data Some string to pass to the function
 * @return Nothing
 */
 
void CanData::processData(string &raw_data)
{
.
.
.
}

Please add yourself to the list of authors, if you make a significant change.