mmcv/CONTRIBUTING.md

## Contributing to OpenMMLab

All kinds of contributions are welcome, including but not limited to the following.

- Fix typo or bugs
- Add documentation or translate the documentation into other languages
- Add new features and components

### Workflow

1. fork and pull the latest OpenMMLab repository
2. checkout a new branch (do not use master branch for PRs)
3. commit your changes
4. create a PR

```{note}
If you plan to add some new features that involve large changes, it is encouraged to open an issue for discussion first.
```

### Code style

#### Python

We adopt [PEP8](https://www.python.org/dev/peps/pep-0008/) as the preferred code style.

We use the following tools for linting and formatting:

- [flake8](https://github.com/PyCQA/flake8): A wrapper around some linter tools.
- [isort](https://github.com/timothycrosley/isort): A Python utility to sort imports.
- [yapf](https://github.com/google/yapf): A formatter for Python files.
- [codespell](https://github.com/codespell-project/codespell): A Python utility to fix common misspellings in text files.
- [mdformat](https://github.com/executablebooks/mdformat): Mdformat is an opinionated Markdown formatter that can be used to enforce a consistent style in Markdown files.
- [docformatter](https://github.com/myint/docformatter): A formatter to format docstring.

Style configurations of yapf and isort can be found in [setup.cfg](./setup.cfg).

We use [pre-commit hook](https://pre-commit.com/) that checks and formats for `flake8`, `yapf`, `isort`, `trailing whitespaces`, `markdown files`,
fixes `end-of-files`, `double-quoted-strings`, `python-encoding-pragma`, `mixed-line-ending`, sorts `requirments.txt` automatically on every commit.
The config for a pre-commit hook is stored in [.pre-commit-config](./.pre-commit-config.yaml).

After you clone the repository, you will need to install initialize pre-commit hook.

```shell
pip install -U pre-commit
```

From the repository folder

```shell
pre-commit install
```

After this on every commit check code linters and formatter will be enforced.

> Before you create a PR, make sure that your code lints and is formatted by yapf.

#### C++ and CUDA

We follow the [Google C++ Style Guide](https://google.github.io/styleguide/cppguide.html).