Coding guidelines for the ALICE O2 project.

• Coding guidelines
• Naming and formatting conventions
• Comments guidelines

The ALICE O2 projects use clang-format to push for a common code formatting. The rules are defined in the clang-format configuration file in this repository (which is propagated to other AliceO2Group repositories). With an adiabatic approach, all changes have to follow the formatting rules. A script, described below, can be used to integrate the formatting into git and suggest formatting only for changed lines.

Note : The installation of clang using aliBuild is not necessary on Mac.

1. Build clang (to be done once)

aliBuild build --defaults o2 Clang

1. Load clang and clang-format

alienv enter Clang/latest

1. Install git-clang-format

cd $HOME
mkdir -p bin
cd bin
wget https://raw.githubusercontent.com/llvm/llvm-project/main/clang/tools/clang-format/git-clang-format
chmod u+x git-clang-format

git clang-format invokes clang-format on the changes in current files or a specific commit. E.g. for the last commit

git clang-format HEAD~1

Or for all commits done with respect to the remote branch state

git clang-format origin/dev

The commands below rely on the .clang-format file located in one of the parent directories of the source files.

Please note that for technical reasons, there are slight differences between clang-format and git-clang-format (see above). All pull requests are checked with git-clang-format as described in the previous bullet. Thus make sure that before pushing code, correct the formatting with git-clang-format. The instructions for clang-format are left here only for reference.

Show correctly formatted version of a file :

clang-format -style=file SOURCEFILE

Directly apply the style to a file :

clang-format -style=file -i SOURCEFILE

Apply the style to all the source and header files in a directory (recursive) :

find . -iname "*.h" -o -iname "*.cpp" | xargs clang-format -style=file -i

Display what needs to be fixed in a file :

clang-format -style=file <SOURCEFILE> | diff <SOURCEFILE> -

A number of config files are available here for various IDEs.

1. Download,
2. Go to File -> Import Settings.

• Q I strongly disagree with rule X !
• A Feel free to contact the WP3 (alice-o2-wp3@cern.ch) to share your concern(s). Rules have already been amended, abandoned or added based on the users feedback. However, please comply with the rules until a change is agreed by CWG11.