micropython-lib/CONTRIBUTING.md

Contributor's Guidelines & Code Conventions

micropython-lib follows the same general conventions as the main MicroPython repository. Please see micropython/CONTRIBUTING.md and micropython/CODECONVENTIONS.md.

Raising issues

Please include enough information for someone to reproduce the issue you are describing. This will typically include:

• The version of MicroPython you are using (e.g. the firmware filename, git hash, or version info printed by the startup message).
• What board/device you are running MicroPython on.
• Which package you have installed, how you installed it, and what version. When installed via mip, all packages will have a __version__ attribute.
• A simple code snippet that demonstrates the issue.

If you have a how-to question or are looking for help with using MicroPython or packages from micropython-lib, please post at the discussion forum instead.

Pull requests

The same rules for commit messages, signing-off commits, and commit structure apply as for the main MicroPython repository.

All Python code is formatted using the black tool. You can run tools/codeformat.py to apply black automatically before submitting a PR. The GitHub CI will also run the ruff tool to apply further "linting" checks.

Similar to the main repository, a configuration is provided for the pre-commit tool to apply black code formatting rules and run ruff automatically. See the documentation for using pre-commit in the code conventions document

In addition to the conventions from the main repository, there are some specific conventions and guidelines for micropython-lib:

• The first line of the commit message should start with the name of the package, followed by a short description of the commit. Package names are globally unique in the micropython-lib directory structure.

  For example: shutil: Add disk_usage function.

• Although we encourage keeping the code short and minimal, please still use comments in your code. Typically, packages will be installed via mip and so they will be compiled to bytecode where comments will not contribute to the installed size.

• All packages must include a manifest.py, including a metadata() line with at least a description and a version.

• Prefer to break larger packages up into smaller chunks, so that just the required functionality can be installed. The way to do this is to have a base package, e.g. mypackage containing mypackage/__init__.py, and then an "extension" package, e.g. mypackage-ext containing additional files e.g. mypackage/ext.py. See collections-defaultdict as an example.

• If you think a package might be extended in this way in the future, prefer to create a package directory with package/__init__.py, rather than a single module.py.

• Packages in the python-stdlib directory should be CPython compatible and implement a subset of the CPython equivalent. Avoid adding MicroPython-specific extensions. Please include a link to the corresponding CPython docs in the PR.

• Include tests (ideally using the unittest package) as test_*.py. Otherwise, provide examples as example_*.py. When porting CPython packages, prefer to use the existing tests rather than writing new ones from scratch.

• When porting an existing third-party package, please ensure that the source license is compatible.

• To make it easier for others to install packages directly from your PR before it is merged, consider opting-in to automatic package publishing (see Publishing packages from forks). If you do this, consider quoting the commands to install packages in your Pull Request description.

Publishing packages from forks

You can easily publish the packages from your micropython-lib fork by opting in to a system based on GitHub Actions and GitHub Pages:

1. Open your fork's repository in the GitHub web interface.
2. Navigate to "Settings" -> "Secrets and variables" -> "Actions" -> "Variables".
3. Click "New repository variable"
4. Create a variable named MICROPY_PUBLISH_MIP_INDEX with value true (or any "truthy" value).
5. The settings for GitHub Actions and GitHub Pages features should not need to be changed from the repository defaults, unless you've explicitly disabled them.

The next time you push commits to a branch in your fork, GitHub Actions will run an additional step in the "Build All Packages" workflow named "Publish Packages for branch".

Anyone can then install these packages as described under Installing packages from forks. The exact commands are also quoted in the GitHub Actions log for the "Publish Packages for branch" step.

Opting Back Out

To opt-out again, delete the MICROPY_PUBLISH_MIP_INDEX variable and (optionally) delete the gh-pages branch from your fork.

Note: While enabled, all micropython-lib packages will be published each time a change is pushed to any branch in your fork. A commit is added to the gh-pages branch each time. In a busy repository, the gh-pages branch may become quite large. The actual .git directory size on disk should still be quite small, as most of the content will be duplicated. If you're worried that the gh-pages branch has become too large then you can always delete this branch from GitHub. GitHub Actions will create a new gh-pages branch the next time you push a change.