(codestyle)=

# Code Style

We use [YAPF](https://github.com/google/yapf) to check Python code style and
apply automatic formatting. We plan to move to [black](https://black.readthedocs.io/en/stable/).

Code should conform to [PEP8](https://www.python.org/dev/peps/pep-0008), the style guide for Python code.
YAPF goes beyond that and applies stylistic changes as configured in the style file {file}`.style.yapf`.
Our maximal line length is 120 but we want to reduce it to 88, the black default.

## Auto-Formatting Python Code

Running {command}`yapf -dr src` shows a diff for the entire source directory.
{command}`yapf -ir src` formats everything in-place (git commit first!).

An alias to auto-format only changed files as seen by Git may be helpful:

```shell
alias py-format-changed="git ls-files -m --others --exclude-standard | grep '\.py$' | xargs yapf -i"
```

## Style Tips

If you want each list value to stay on a separate line, use a trailing comma after
the last element (here after `'created_at'`):

```python
model_properties = [
    'abstract',
    'author',
    'ballot',
    'content',
    'created_at',
]
```

## More About Code Style

- Recommended talk: [Raymond Hettinger - Beyond PEP 8 -- Best practices for beautiful intelligible code - PyCon 2015](https://www.youtube.com/watch?v=wf-BqAjZb8M)