doc/codingstd.txt
author Mathieu Lacage <mathieu.lacage@sophia.inria.fr>
Thu, 17 Apr 2008 15:40:25 -0700
changeset 2971 75780f899be3
parent 657 be551a3b07c6
permissions -rw-r--r--
output the initial value of the attributes

       The Ns-3 Coding Style

/*
 * Note:  This file is incomplete and will be converted to non-text (html,pdf)
 * formats at a future date
 */

1) Code layout
     -----------

The code layout follows the GNU coding standard layout for C and extends
it to C++. Do not use tabs for indentation. Indentation spacing is 2
spaces as outlined below:

void 
Foo (void)
{
  if (test)
    {
      // do stuff here
    }
  else
    {
      // do other stuff here
    }

  for (int i = 0; i < 100; i++)
    {
      // do loop
    }

  while (test)
    {
      // do while
    }

  do
    {
      // do stuff
    } while ();
}

The following is not recommended:

if (test) statement

if (test)
  statement

for (...) statement

Each statement should be put on a separate line to increase readability.
Short one-line comments can use the C++ comment style, that is, '//'
but longer comments should use C-style comments:
/*
 *
 *
 */


2) Naming Patterns
   ---------------

2.1) Name encoding
     -------------
Function, Method, and Type names should follow the CamelCase convention:
words are joined without spaces and are capitalized. For example,
"my computer" is transformed into MyComputer. Do not use all capital 
letters such as MAC or, PHY, but choose instead Mac or Phy. Do not use
all capital letters, even for acronyms such as EDCA: use Edca instead.
The goal of the CamelCase convention is to ensure that the words which
make up a name can be separated by the eye: the initial Caps fills
that role.

Variable names should follow a slight variation on the base CamelCase
convention: camelBack. For example, the variable "user name" would be
named "userName". This variation on the basic naming pattern is used to
allow a reader to distinguish a variable name from its type. For example,
"UserName userName;" would be used to declare a variable named userName
of type UserName.

Global variables should be prefixed with a "g_" and member variables
(including static member variables) should be prefixed with a "m_". The
goal of that prefix is to give a reader a sense of where a variable of
a given name is declared to allow the reader to locate the variable 
declaration and infer the variable type from that declaration. For example
you could declare in your class header my-class.h:

class MyClass
{
  void MyMethod (int aVar);
  int m_aVar;
  static int m_anotherVar;
};

and implement in your class file my-class.cc:

int MyClass::m_anotherVar = 10;
static int g_aStaticVar = 100;
int g_aGlobalVar = 1000;

void
MyClass::MyMethod (int aVar)
{
  m_aVar = aVar;
}

2.2) Choosing names

Variable, function, method, and type names should be based on the
english language. Furthermore, always try to choose descriptive
names for them. Types are often english names such as: Packet, 
Buffer, Mac, or Phy. Functions and Methods are often named
based on verbs and adjectives: GetX, DoDispose, ClearArray, etc.

A long descriptive name which requires a lot of typing is always
better than a short name which is hard to decipher. Do not use
abbreviations in names unless the abbreviation is really unambiguous
and obvious to everyone. Do not use short inapropriate names such
as foo, bar, or baz. The name of an item should always match its 
purpose. As such, names such as tmp to identify a temporary
variable or such as 'i' to identify a loop index are ok.

3) File layout and code organization
   ---------------------------------

A class named MyClass should be declared in a header named my-class.h
and implemented in a source file named my-class.cc. The goal of this
naming pattern is to allow a reader to quickly navigate through
the ns-3 codebase to locate the source file relevant to a specific
type.

Each my-class.h header should start with the following comments: the
first line ensures that developers who use the emacs editor will be 
able to indent your code correctly. The following lines ensure that
your code is licensed under the GPL, that the copyright holders
are properly identified (typically, you or your employer), and
that the actual author of the code is identified. The latter is
purely informational and we use it to try to track the most
appropriate person to review a patch or fix a bug.

/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/*
 * Copyright (c) YEAR COPYRIGHTHOLDER
 * 
 * 3-paragran GPL blurb
 *
 * Author: MyName <myemail@foo.com>
 */

Below these C-style comments, always include the following which
defines a set of header guards (MY_CLASS_H) used to avoid multiple
header includes, which ensures that your code is included
in the "ns3" namespace and which provides a set of doxygen comments
for the public part of your class API. Detailed information
on the set of tags available for doxygen documentation is described
in the doxygen website: http://www.doxygen.org.

#ifndef MY_CLASS_H
#define MY_CLASS_H

namespace n3 {

/**
 * \brief short one-line description of the purpose of your class
 *
 * A longer description of the purpose of your class after a blank
 * empty line.
 */
class MyClass
{
public:
 MyClass ();
 /**
  * \param firstParam a short description of the purpose of this parameter
  * \returns a short description of what is returned from this function.
  *
  * A detailed description of the purpose of the method.
  */
 int DoFoo (int firstParam);
private:
 void MyPrivateMethod (void);
 int m_myPrivateMemberVariable;
};

} // namespace ns3

#endif /* MY_CLASS_H */

The my-class.cc file is structured similarly:

/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/*
 * Copyright (c) YEAR COPYRIGHTHOLDER
 * 
 * 3-paragran GPL blurb
 *
 * Author: MyName <myemail@foo.com>
 */
#include "my-class.h"

namespace ns3 {

MyClass::MyClass ()
{}

...

} // namespace ns3