Git Branching #

This section builds on the previous Git Fundamentals section.

If you have not done that section you should still be able to do all the exercises here since each one starts with a script to get you to a known starting state.

Tip: Preventing Data Loss #

A vast majority of git commands are non-destructive. Most things you do can be undone. But when dealing with complex branch operations or other unfamiliar commands you may want to take extra precautions to prevent data loss

With that in mind, below you will find my #1 tip for protecting yourself when you are doing things that are scary in git:

cp -rp ./my-repo ./my-repo.bak

copy my-repo my-repo.bak

Ok, so it’s just a copy. Not very fancy or efficient but it works. As you become more familiar with git you might not do this as often. But when in doubt, take a few seconds nad make a backup. Then no matter what you do you can recover.

Tip: Kinds of Git Diagrams #

So far we have seen and used 2 kinds of git diagrams. But the exercises in this section are going to use a 3rd.

Traditional Diagrams #

The fundamentals section ended with a repo that looks something like this:

%%{init: { 'theme': 'neutral' } }%% gitGraph commit id: "Initial add" tag: "v0.0.1" commit id: "feat: add api" branch topic commit id: "feat: add users" checkout main commit id: "feat: add docs"

These diagrams are great! And they are really the only accurate way to represent the data as it exists in git.

In fact, you will find a lot of these in the git book. Here is another example from the git book:

We could make this same graph using our mermaid gitGraph

%%{init: { 'theme': 'neutral', 'gitGraph': {'showBranches': true, 'showCommitLabel':true,'mainBranchName': 'master'} } }%% gitGraph commit id: "C0" commit id: "C1" commit id: "C2" branch iss53 commit id: "C3" checkout master commit id: "C4" checkout iss53 commit id: "C5" checkout master merge iss53 id: "C6"

But I think we can do a bit better when it comes to visualizing the state you need to understand when dealing with some git branching workflows. So we are going to introduce…

Stack Diagrams #

As we work through the branching section of the workshop we are going to visualize our operations using a more simplified version of these diagrams.

Essentially git branches will simply be represented as stacks of commits. You can see that this is just a slightly different way to describe the same data as before:

Stack Diagrams Cannot Always Accurate Express Git State

We will be using them here because

• They make visualizing certain processes easier
• They more closely match what you see in git log or during an interactive rebase

BUT data is lost in some cases. If you look at the comparison above, you will see that they you lose some data on merge. Stack diagrams, like git log have to decide how to sort commits across trees and there is no exact answer. But they are a useful tool for understanding some of the concepts we will cover here.

Wrapping Up #

This section covered just a few of the basic concepts like

• git remotes
• multiple branches
• stack diagrams

Next we will build on this to help you understand how to keep branches up to date and get branch changes back to the main branch