Code Formatting

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Also known as ‘linting’. This is used to ensure a consistent code format throughout Iris, maximising the maintainability and quality. Code formatting is checked using the pre-commit tool, and the full list current formatting tools is defined in Iris’ pre-commit-config.yaml file. Read more about linting on the SciTools wiki page.

pre-commit compliance is automatically checked on all Iris pull requests (more info: pre-commit CI), but you can also run pre-commit locally as Git hooks - every time you make a commit. Read on to learn more about local running.

You can install pre-commit in your development environment using pip:

$ pip install pre-commit

or alternatively using conda:

$ conda install -c conda-forge pre-commit

Note

If you have setup your Python environment using the guide Installing a Development Version then pre-commit should already be present.

In order to install the pre-commit git hooks defined in our .pre-commit-config.yaml file, you must now run the following command from the root directory of Iris:

$ pre-commit install

Upon performing a git commit, your code changes will be automatically checked against all Iris’ pre-commit hooks. For some hooks this includes automated edits of your code e.g. formatting or sorting of imports; these new edits are not staged for you - i.e. you need to run git add again on that file. Note that, pre-commit will automatically download and install the necessary packages for each .pre-commit-config.yaml git hook.

With the pre-commit configured, the output of performing a git commit will look similar to:

Check for added large files..............................................Passed
Check for merge conflicts................................................Passed
Debug Statements (Python)............................(no files to check)Skipped
Don't commit to branch...................................................Passed
black................................................(no files to check)Skipped
flake8...............................................(no files to check)Skipped
[contribution_overhaul c8513187] this is my commit message
2 files changed, 10 insertions(+), 9 deletions(-)

Type Hinting

Iris is gradually adding type hints into the codebase. The reviewer will look for type hints in a pull request; if you’re not confident with these, feel free to work together with the reviewer to add/improve them.