Notes on Version Control

My notes from Tobias Gunther’s video covering tools and concepts for version control with git.

Christian Mills


December 29, 2021


Here are some notes I took while watching Tobias Gunther’s video covering tools and concepts for mastering version control with git.

The Perfect Commit

  • Add the right changes
    • Goal is to make a commit that makes sens
    • Should only contain changes from a single topic
    • Don’t cram everything into single commit
      • Makes it more difficult to what changes were made in retrospect
    • Use Git staging area concept
      • allows you to select specific files or parts of files for the next commit
    • include specific file
      • git add <filepath>
    • include part of a file
      • git add -p <filepath>
      • steps through every chunk of change in the file and asks whether to add it
  • Compose a good commit message
    • Subject: concise summary of what happened
      • If you are struggling to keep it short, you might have too many topics in the commit
      • Example: “Add captcha for email signup”
    • Body: more detailed explanation
      • What is now different than before?
      • What is the reason for the change?
      • Is there anything to watch out for or is there anything particularly remarkable?
      • Add an empty line after the subject to let git know that you are now writing the body
      • Example:
        • Email signups now require a captcha to be completed:
          • signup.php uses our captcha library
          • invalid signup attempts are now blocked

Branching Strategies

  • Need to have a clear convention for how your team will work with branches
  • Git allows you to create branches, but does not tell your how to use them
  • You need a written best practice of how work is ideally structured in your team to avoid mistakes and collisions
  • Your branching workflow is highly dependent on your team, size of team, your project, and how you handle releases
  • Having a clear convention for branches helps onboard new team members
  • Consider your project, release cycle, and team
  • Take inspiration from existing branching strategies and create your own

Integrating Changes & Structuring Releases

  • The best approach depends on the needs and requirements of your team and project
  • Option 1: Mainline development
    • New code is integrated quickly into the mainline, production code
    • few branches
    • relatively small commits
      • cannot risk big and bloated commits when constantly integrating into production code
    • high-quality testing and QA standards
  • Option 2: State, Release, and Feature Branches
    • branches enhance structures and workflows
    • different types of branches fulfill different types of jobs
      • features and experiments are kept in different branches
      • releases can be planned and managed in their own different branches
      • different states in the development workflow can be represented by branches

Types of Branches

  • Long running
    • exist through the complete lifetime of the project
    • often, they mirror “stages” in your dev life cycle
    • common convention connected to long running branches
      • often no direct commits
      • commits are only added through merges or rebases
      • you don’t want to add untested code to production
      • might want to release new code in batches
  • Short-lived
    • for new features, bug fixes, refactorings, experiments
    • will be deleted after integration (merge/rebase)
    • typically based on a long running branch

Two Example Branching Strategies

  • GitHub Flow
    • very simple, very learn
    • only one long running branch (”main”) + feature branches
  • GitFlow
    • more structure, more rules
    • long-running: “main” + “develop”
      • main: a relfection of the current production state
      • develop: feature branches are based on it and will be merged back into it
        • also the starting point for any new releases
        • production ready versions are merged into main
    • short-lived: features, releases, hotfixes

Pull Requests

  • pull request are not a core git feature
  • they are provided by your git hosting platform
  • will work and look a bit different on different platforms
  • without a pull request, you would jump right to merging your code
  • they are a way to communicate about code and review it
  • a way to contribute code to repositories you don’t have write access to
    • fork: your personal copy of a repository
      • You can make changes in your forked version and open a pull request to include those changes into the original
  • pull requests are based on branches, not individual commits
  • push branch to your remote fork
    • git push --set-upstream <remote-branch> <local-branch>
  • request to include changes in original repository

Merge Conflicts

  • When they might occur
    • when integrating commits from different sources
      • git merge
      • git rebase
      • git pull
      • git stash apply
      • git cherry-pick
    • Git will mostly figure things out on its own
    • Can happen when contradictory changes happen
      • Git cannot decide which change it should keep
    • Git will immediately tell you when a conflict has occurred
    • Existing conflicts can be view with git status
  • What they actually are
    • just characters in a file
    • Git marks the problematic areas in a file
  • How to solve them
    • Undo a merge
      • git merge --abort
    • Undo a rebase
      • git rebase --abort
    • Clean up files that have been marked by Git

Merge versus Rebase

  • Merge
    • Git looks for three commits
      • The common ancestor commit
      • The last commit on branch A
      • The last commit on branch B
    • Git creates a new commit that contains the differences between branch A and B
      • called a merge commit
      • automatically generated
      • would need to look at the commit history for both branches
  • Rebase
    • not better or worse than merge, just different
    • makes history look like a straight line of commits without any branches
    • rewrites commit history
    • Steps
      • Git removes all commits on branch A and temporarily saves them
      • Git applies new commits from branch B
      • New commits from branch A are positioned on top of the commits from branch B
    • Do not rebase commits that you have already pushed to a shared repository
    • Use it for cleaning up your local commit history before merging it into a shared team branch