Git

Even more important this semester

Version control

• Keeps track of the history of changes

• Allows branching of history

• Lets us compare different branches.

• Helps to merge branches back together

Normal development cycle

• Make a feature branch

• Make changes to files

• Periodically commit changes to branch

• Push (sync) branch to Github

• Make a PR and request review

• After PR approved, merge to main

• Optionally, delete the feature branch

What is a branch?

• A named version of all the files in your repository

• Different branches can have different contents

• Allows you to work on different things without them interfering with each other.

• In multi-person projects even more important.

Commits

• Commits are how you save work in git.

• You might make several changes in multiple files before you commit them.

• Each time you make a commit, you will write a short description of the commit.

• Each new commit is added to the current branch.

Some commit messages

A special branch: main

• The main branch is what its name says.

• Ultimately we want all the code you write to end up in main.

• But code starts out in “feature branches”

Merging

• Merging is the process of adding the commits made in one branch (usually a feature branch) to another branch (usually main.)

• If the changes don’t textually conflict, things merge automatically

• That should almost always be the case for you.

Pull requests

• A Github feature for looking at the changes you’ve made on one branch that you want to merge into another.

• Allows reviewing, commenting, approval, etc.

• The main mechanism for communicating about code in open source projects and many companies.

• And in this class.

Our branch naming convention

• Name branches for the directory where the new code will live e.g. projects/whatever

• This ensures that code from the projects/whatever branch will never conflict with code from other project branches.

Continuing work on a feature branch

• After you merge your feature branch PR to main you can keep working on the same branch if you don’t delete it.

• Or you can create a new branch with the same name if you did.

• New PRs will only include the new changes.

Git guidelines

• Submit PRs for review regularly.

• Merge PRs as soon as they are approved.

• If I request changes, you should work on those things and re-request review.

• Delete old branches when you are done with a project or putting it down for a while.

• Don’t work on too many projects at once. Ideally one at a time.

This semester

• You will spend more time working on projects than on problem sets.

• To do your work you will have to deal with git and Github.

• We are going to start using a new development environment called Codespaces that is provided by Github.

But first

Spring cleaning