Git Introduction

Source Control

In a nutshell:

• It's really useful to save your code somewhere that isn't just on your local computer, in case your computer dies
• If all your code is somewhere where everybody can reach it, that means everybody can work on it together
• If you keep backups of what your code was like in the past, you can go back to it if you messed something up now.

Advanced:

• We call the code the "source code." Since we want to keep it under control (backed up, available, etc), we call solutions to this problem "Source Control."
• Source control systems such as Git or SVN let us easily back up our code and collaborate together

Git

Git is the specific source control system we use. A few terms you'll see constantly:

• Repository (or "repo") - a project's folder of code, plus the entire history of every change ever made to it. XbotEdu is a repository.
• Clone - make a copy of a repository on your own computer so you can work on it. See Use GitHub Desktop to clone.
• Commit - a saved snapshot of your changes, with a short message describing what you did. Commits are the "backups of what your code was like in the past" from above.
• Branch - a separate line of commits. You make a branch so your half-finished work doesn't disturb everyone else. The main branch is called main.
• Push / Pull - send your commits up to the shared copy, or bring other people's commits down to yours.
• Merge - combine the commits from one branch into another.

You don't have to memorize these. Most of what you'll do day to day is: make a branch, make some commits, push them, and open a pull request.

Most people on the team use GitHub Desktop, which does all of the above with buttons instead of typed commands. Using Git from the terminal is a good thing to learn eventually, but it isn't required.

github.com

Git keeps the history; GitHub is the website that hosts the shared copy everyone works from. Our code lives in the Team 488 organization.

GitHub also adds things Git itself doesn't have:

• Forks - your own copy of someone else's repository on GitHub. The curriculum has you work in a fork of XbotEdu, so you can experiment without affecting the original.
• Pull requests - how you propose that your branch be merged, and how teammates review your code first. See Making a Pull Request.
• Issues - a place to track bugs and work to be done.

If you want a more thorough introduction, GitHub's own Hello World guide walks through branches, commits and pull requests in about 15 minutes.