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Contributing to Cantera

  • For significant changes, please start a discussion on the Cantera Users' Group or create an issue on the Cantera/enhancements repository on GitHub to plan your modifications so that they can be implemented efficiently and in a way that doesn't conflict with any other planned future development

  • Fork the Cantera/cantera repository on Github

  • Clone your new repository or add it as a remote to an existing repository

  • Check out the existing main branch, then start a new feature branch for your work

  • When making changes, write code that is consistent with the surrounding code (see the style guidelines below)

  • Add tests for any new features that you are implementing to either the GoogleTest-based test suite or the Python test suite.

  • Add examples that highlight new capabilities, or update existing examples to make use of new features.

  • As you make changes, commit them to your feature branch

    • Configure Git with your name and e-mail address before making any commits
    • Use descriptive commit messages (summary line of no more than 72 characters, followed by a blank line and a more detailed summary, if any)
    • Make related changes in a single commit, and unrelated changes in separate commits
    • Make sure that your commits do not include any undesired files, such as files produced as part of the build process or other temporary files.
    • Use Git's history-rewriting features (such as git rebase -i; see to organize your commits and squash "fixup" commits and reversions.
    • Do not merge your branch with main. If needed, you should rebase your branch onto the most recent HEAD commit of main.
    • Periodically run the test suite (scons test) to make sure that your changes are not causing any test failures.
  • Push the changes on your new feature branch to your forked copy of the Cantera/cantera repository on GitHub.

  • Submit a Pull Request on Github, from your forked copy. Check the results of the continuous-integration tests run using GitHub Actions and resolve any issues that arise.

  • Additional discussion of good Git & Github workflow is provided at and

  • Cantera is licensed under a BSD license which allows others to freely modify the code, and if your Pull Request is accepted, then that code will be release under this license as well. The copyright for Cantera is held collectively by the contributors. If you have made a significant contribution, please add your name to the AUTHORS file.

Style Guidelines

  • Try to follow the style of surrounding code, and use variable names that follow existing patterns. Pay attention to indentation and spacing.
  • Configure your editor to use 4 spaces per indentation level, and never to use tabs.
  • Avoid introducing trailing whitespace
  • Limit line lengths to 88 characters when possible
  • Write comments to explain non-obvious operations
  • Use whitespaces to improve code readability (examples: after commas; before and after mathematical operators (+/-/*// except ^), binary operators (&&/||/...), and comparisons (</>/==/...); before and after equality signs = unless used for the assignment of a default parameter)
  • Do not go out of your way to change formatting in otherwise unmodified code
  • Write 'for example', 'such as', or 'that is' instead of using the Latin abbreviations 'i.e.' and 'e.g.'.


  • All classes, member variables, and methods should have Doxygen-style comments (for example, comment lines starting with //! or comment blocks starting with /*!; do not use /// or /** in new code)
  • Doxygen-style groupings should bracket code using //! @{ and //! @}
  • Avoid defining non-trivial functions in header files
  • Header files should include an 'include guard'
  • Protected and private member variable names are generally prefixed with m_. For most classes, member variables should not be public.
  • Class names use InitialCapsNames
  • Methods use camelCaseNames
  • Do not indent the contents of namespaces
  • Code should follow the C++11 standard, with minimum required compiler versions GCC 4.8, Clang 3.4, MSVC 14.0 (2015) and Intel 15.0.
  • Avoid manual memory management (that is, new and delete), preferring to use standard library containers, as well as std::unique_ptr and std::shared_ptr when dynamic allocation is required.
  • Portions of Boost which are "header only" may be used. If possible, include Boost header files only within .cpp files rather than other header files to avoid unnecessary increases in compilation time. Boost should not be added to the public interface unless its existence and use is optional. This keeps the number of dependencies low for users of Cantera. In these cases, CANTERA_API_NO_BOOST should be used to conditionally remove Boost dependencies.
  • While Cantera does not specifically follow these rules, the following style guides are useful references for possible style choices and the rationales behind them.
  • For any new code, do not use the doublereal and integer typedefs for the basic types double and int, but also do not go out of your way to change uses of these in otherwise unmodified code.


  • Style generally follows PEP8 (
  • Code in .py and .pyx files needs to be written to work with Python 3
  • The minimum Python version that Cantera supports is Python 3.6, so code should only use features added in Python 3.6 or earlier
  • Please use double quotes in all new Python code