Introduction

Last updated on 2024-06-27 | Edit this page

Overview

Questions

  • “What are Pull Requests (PRs)?”
  • “How do PRs help with software development?”

Objectives

  • “Become familiar with the purpose of PRs.”

What are Pull Requests?

To borrow from Rachel Garner, “Software developers use pull requests, otherwise known as PR, to initiate the process of integrating new code changes into the main project repository. Pull requests are sent through git systems, like GitLab, GitHub, and BitBucket, to notify the rest of your team that a branch or fork is ready to be reviewed.”

Image from Undraw.co for version control visualization

In other words, PRs are a mechanism for introducing and merging changes into a code base in a manner that enables discussion and collaboration.

In this lesson, students will learn about better practices for GitHub PRs.

How Pull Requests Fit in the Development Process

From Freira et al.: Visualization of the GitHub development workflow with PRs

The development workflow can have several different formats; however, a simple one is this:

  1. Create a feature branch
  2. Make changes and commit back to the feature branch
  3. Open a Pull request

The Benefits of Pull Requests

Integrating PRs into the development process has numerous benefits. Some of the main ones are:

  • Collaboration: Pull requests provide a location for other developers to see and comment on proposed changes. This encourages collaboration and discussion.
  • Reduce risks: Other team members are able to review proposed changes and make suggestions, find potential risks, etc.
  • Improve quality: No one person knows better than a group. Using PRs allows a crowd to get involved and improve the quality of the code.

GitHub Pull Requests

Numerous different merging systems exist - both commercial and open-source, integrated and stand-alone.

GitHub integrates branching and merging into their version control system. Every project on GitHub can use the integrated pull requests feature.

INTERSECT training repository navigation bar

To access a repository’s PRs, simply navigate to the repository root page and click on “Pull requests” in the navigation bar. This will take you to the page of all “Open” PRs.

Click on a PR to open it and see its details, plus any discussion.

Browsing Open PRs

Navigate to https://github.com/spack/spack and find the pull requests page.

  • How many PRs are currently open?
  • How many have been closed?
  • Who is the author of the top-most PR?

Key Points

  • “Pull Requests are a way to control the introduction of new content into a shared repository.”
  • “Pull Requests enable better collaboration for multiple developers.”