C++ Coding Guidelines


  • Class names are CamelCase, beginning with a capital letter.
  • Constant names are ALL_CAPITALS with underscores separating words.
  • Method, method parameter and local variable names are lowercase with underscores separating words, e.g. method_name.
  • Member variable names are lowercase with underscores separating words and also begin with an underscore, e.g. _member_variable.

C++ Feature Use

  • We assume a C++11-compliant compiler, so C++11 features are allowed with some exceptions.
  • No use of auto type declarations.
  • No use of using namespace ..., if the namespace is particularly lengthy, consider using namespace aliasing (e.g. namespace po = boost::program_options).
  • Avoid using Boost (or similar) libraries that return special library-specific pointers, to minimize “infection” of the code-base. Consider using the C++11 equivalents instead.


C++ code contributed to Clearwater should be formatted according to the following conventions:

  • Braces on a separate line from function definitions, if statements, etc.
  • Two-space indentation
  • Pointer operators attached to the variable type (i.e. int* foo rather than int *foo)
  • if blocks must be surrounded by braces

For example:

if (x)
       int *foo = do_something();

will be replaced with

if (x)
 int* foo = do_something();

It’s possible to fix up some code automatically using astyle, with the options astyle --style=ansi -s2 -M80 -O -G -k1 -j -o. This fixes up a lot of the most common errors (brace style, indentation, overly long lines), but isn’t perfect - there are some cases where breaking the rules makes the code clearer, and some edge cases (e.g. around switch statements and casts on multiple lines) where our style doesn’t always match astyle’s.

Language Features

  • Use of the auto keyword is forbidden.


Where it is necessary to document the interface of classes, this should be done with Doxygen-style comments - three slashes and appropriate @param and @returns tags.

/// Apply first AS (if any) to initial request.
// See 3GPP TS 23.218, especially s5.2 and s6, for an overview of how
// this works, and 3GPP TS 24.229 s5.4.3.2 and s5.4.3.3 for
// step-by-step details.
// @Returns whether processing should stop, continue, or skip to the end.
AsChainLink::on_initial_request(CallServices* call_services,