Pre-Commit Workshop

The slides are licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. Any code files in this repository are distributed under the Apache-2.0 license.

Abstract

Maintaining code quality can be challenging, no matter the size of your project or number of contributors. Different team members may have different opinions on code styling and preferences for code structure, while solo contributors might find themselves spending a considerable amount of time making sure the code conforms to accepted conventions. However, manually inspecting and fixing issues in files is both tedious and error-prone. As such, computers are much more suited to this task than humans. Pre-commit hooks are a great way to have a computer handle this for you.

Pre-commit hooks are code checks that run whenever you attempt to commit your changes with git. They can detect and, in some cases, automatically correct code-quality issues before they make it to your code base. In this tutorial, you will learn how to install and configure pre-commit hooks for your repository to ensure that only code that passes your checks makes it into your code base. We will also explore how to build custom pre-commit hooks for novel use cases.

Setup Instructions

1. Fork and clone this repository. If you don't have a GitHub account, you will need to create one to complete this step. Please be sure to check for changes (and sync them) before coming to the workshop.

2. Create a virtual environment using Python 3.10 or higher on your personal laptop, and install pre-commit in that virtual environment. You can use the tool of your choice (e.g., venv, conda, uv), but do not attempt to install the project itself.

   Using venv

   On Linux or MacOS:

   python -m venv venv
   source venv/bin/activate
   python -m pip install -U pip  # please make sure you have pip>=25.1
   python -m pip install pre-commit

   See https://docs.python.org/3/library/venv.html for more information and the Windows equivalent if you decide to use venv.

   Using uv

   Note that this will install pre-commit as a tool for global use:

   uv python install  # install the Python version in .python-version, if not already installed
   uv tool install pre-commit --with pre-commit-uv

3. Think about some potential ideas for the pre-commit hook you would like to create in the second half of the workshop. Some ideas to get you started: prohibit print() calls, enforce file naming conventions, block large files, keep files under a certain number of lines, check for missing docstrings, disallow certain imports, etc.

About the Author

Stefanie Molin (@stefmolin) is a software engineer at Bloomberg in New York City, where she tackles tough problems in information security, particularly those revolving around data wrangling/visualization, building tools for gathering data, and knowledge sharing. She is also a core developer of numpydoc and the author of Hands-On Data Analysis with Pandas, which is currently in its second edition and has been translated into Korean and Chinese. She holds a bachelor’s of science degree in operations research from Columbia University's Fu Foundation School of Engineering and Applied Science, as well as a master’s degree in computer science, with a specialization in machine learning, from Georgia Tech. In her free time, she enjoys traveling the world, inventing new recipes, and learning new languages spoken among both people and computers.

Licenses

Code

Any code files in this repository are distributed under the Apache-2.0 license.

Slides

The slides are licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.