Style Guide

Files and Directories

File names are made of a base name and an optional period and suffix. The base name should be a noun, in mixed case with the first letter of each internal word capitalized. It should also reflect the name of the class or module implemented. The following suffixes are mandatory:

• C source file names must end in .c

• C included header file names must end in .h

• C++ source file names must end in .cpp

• C++ included header file names must end in .hpp

• Bourne/BASH shell scripts must end in .sh

• CMake scripts, with the exception of CMakeLists.txt, must end in .cmake

Source Code

The language of choice for writing code and documentation is English and you should not use other languages.

Do not use "underhanded names" (ones that begin with an underscore), this convention is reserved to the compiler and standard library implementations.

Class and structures names should be nouns, in mixed case with the first letter of each internal word capitalized. Try to keep your class names simple and descriptive. Use whole words. Avoid acronyms and abbreviations, unless the abbreviation is much more widely used than the long form, such as UDP or CAN. (eg UDPSocket).

Functions and member functions should be verbs, in mixed case with the first letter lowercase and the first letter of each internal word capitalized. (eg dumpRegisters).

Variable names should be short yet meaningful. All characters should be lowercase with underscores separating words (eg. dry_run). The choice of a variable name should be mnemonic, that is, designed to indicate to the casual observer the intent of its use. One-character variable names should be avoided except for temporary "throwaway" variables. Common names for temporary variables are i, j, k, m, and n for integers; c, d, and e for characters.

Member variables should be prefixed with "m_" (eg. m_handle) and constant variables should be prefixed with "c_" (eg. c_max_size). The names of preprocessor constants and macros should be all uppercase with words separated by underscores (eg. MAX_BUFFER_SIZE). Indentation is performed using the ASCII space character and never with ASCII horizontal tabs. Each source file must start with the following preamble, with one author per line and an optional sentence describing his/her work in the file. The blank line after the comment box is mandatory.

//***************************************************************************
// Copyright 2007-2013 Universidade do Porto - Faculdade de Engenharia      *
// Laboratório de Sistemas e Tecnologia Subaquática (LSTS)                  *
//***************************************************************************
// This file is part of DUNE: Unified Navigation Environment.               *
//                                                                          *
// Commercial Licence Usage                                                 *
// Licencees holding valid commercial DUNE licences may use this file in    *
// accordance with the commercial licence agreement provided with the       *
// Software or, alternatively, in accordance with the terms contained in a  *
// written agreement between you and Universidade do Porto. For licensing   *
// terms, conditions, and further information contact lsts@fe.up.pt.        *
//                                                                          *
// European Union Public Licence - EUPL v.1.1 Usage                         *
// Alternatively, this file may be used under the terms of the EUPL,        *
// Version 1.1 only (the "Licence"), appearing in the file LICENCE.md       *
// included in the packaging of this file. You may not use this work        *
// except in compliance with the Licence. Unless required by applicable     *
// law or agreed to in writing, software distributed under the Licence is   *
// distributed on an "AS IS" basis, WITHOUT WARRANTIES OR CONDITIONS OF     *
// ANY KIND, either express or implied. See the Licence for the specific    *
// language governing permissions and limitations at                        *
// https://www.lsts.pt/dune/licence.                                        *
//***************************************************************************
// Author: Ricardo Martins                                                  *
//***************************************************************************

C++ Header Files

Header files should be self-sufficient. Moreover ensure that each header file is compilable standalone, by having it include any headers its contents depend upon. Use the script programs/scripts/dune-maintainer-checks.py to check if the headers available in the repository have this property.

Always write conditional inclusion guards, and remember that the guard's macro name should be unique among all source files and reflect it's parent directory and namespace. The guard's macro name shall end with _HPP_INCLUDED_. Header guards do not count for the indentation of preprocessor statements. For example the contents of the header file src/DUNE/Hardware/DeviceDriver.hpp should have the following layout:

//***************************************************************************
// Copyright 2007-2013 Universidade do Porto - Faculdade de Engenharia      *
// Laboratório de Sistemas e Tecnologia Subaquática (LSTS)                  *
//***************************************************************************
// This file is part of DUNE: Unified Navigation Environment.               *
//                                                                          *
// Commercial Licence Usage                                                 *
// Licencees holding valid commercial DUNE licences may use this file in    *
// accordance with the commercial licence agreement provided with the       *
// Software or, alternatively, in accordance with the terms contained in a  *
// written agreement between you and Universidade do Porto. For licensing   *
// terms, conditions, and further information contact lsts@fe.up.pt.        *
//                                                                          *
// European Union Public Licence - EUPL v.1.1 Usage                         *
// Alternatively, this file may be used under the terms of the EUPL,        *
// Version 1.1 only (the "Licence"), appearing in the file LICENCE.md       *
// included in the packaging of this file. You may not use this work        *
// except in compliance with the Licence. Unless required by applicable     *
// law or agreed to in writing, software distributed under the Licence is   *
// distributed on an "AS IS" basis, WITHOUT WARRANTIES OR CONDITIONS OF     *
// ANY KIND, either express or implied. See the Licence for the specific    *
// language governing permissions and limitations at                        *
// https://www.lsts.pt/dune/licence.                                        *
//***************************************************************************
// Author: Ricardo Martins                                                  *
//***************************************************************************

#ifndef DUNE_HARDWARE_DEVICE_DRIVER_HPP_INCLUDED_
#define DUNE_HARDWARE_DEVICE_DRIVER_HPP_INCLUDED_

...

#endif

Formatting Source Code

Pointer/reference declarations:

char* pointer;
char& reference;
void (*function_pointer)(void);
void (Type:: *pointer_to_member_function)(void);

Type definitions:

typedef char* str_t;
typedef void (function_t)(void);
typedef void (Type:: *member_function_t)(void);

Array initialization:

char* members[] = {"one", "two"};

Multiline array initialization:

char* members[] =
{
  "one",
  "two",
  "three"
};

C-Style casts:

n = (char*)var;
x = (char*)&y;

Function declaration:

static char*
function(char* s1, char* s2);

Function definition:

char*
function(char* s1, char* s2)
{
  function-body;
}

Function call:

n = function(str0, str1);

Single line if statement:

if (if-condition)
  if-line;
else if (else-if-condition)
  else-if-line;
else
  else-line;

Multiline if statement:

if (condition)
{
  if-block;
}
else
{
  else-block;
}

Single line while statement:

while (condition)
  while-line;

Multiline while statement:

while (condition)
{
  while-block;
}

Single line for statement:

for (initialization; stop-condition; increment)
  for-line;

Multiline for statement:

for (initialization; stop-condition; increment)
{
  for-block;
}

Single line do while statement:

do
  do-while-line;
while (condition);

Multiline line do while statement:

do
{
  do-while-line;
}
while (condition);

Try/catch statement:

try
{
  try-block;
}
catch (variable)
{
  catch-block;
}

Switch statement:

switch (variable)
{
  case A:
    a-statement;
    break;
  case B:
    b-statement;
    break;
  default:
    default-statement;
    break;
}

Class declaration:

class Example
{
public:
  public-block;

protected:
  public-block;

private:
  public-block;
};

Namespace declaration:

namespace DUNE
{
  namespace-contents;
}

Preprocessor conditional statement:

#if defined(MACRO)
#  define MACRO_DEF
#else
#  define MACRO_UND
#endif

Preprocessor header inclusion:

// DUNE headers.
#include <DUNE/Config.hpp>
#include <DUNE/Concurrency/Initializer.hpp>

// POSIX headers.
#if defined(DUNE_SYS_HAS_PTHREAD_H)
#  include <pthread.h>
#endif