Collaborating using github

Remote repository

• central location everyone can see
• requires internet
• github, bitbucket, gitlab
• public vs private

Getting Ready

• go to github.com
• sign into your account
• In your terminal, make sure that you are in your toy_repo directory
• Click your "yes" button when you're done

Create a new repository

• Press the + sign and select "New Repository

• Call your repo toy_repo and "create repository"
• Follow the directions to push an existing repository
• click your "yes" button when you're finished

• Copy and Paste this section into the terminal where you created your local repository
• remote add... gives the nickname 'origin' to the url to the remote repository
• git push -u ... creates remote branch on origin called master

Connect your remote and local repositories

Exercise: Explore your remote repository

• at the top of the page click yourname/toy_repo

More information

• what branch am I on?
  •  
  • default: master
• what is my remote repository?
  •  
  • default nickname: origin

Collaborating with people you trust

• write access to collaborators
• simultaneously edit
• merge changes

Merge #1

• Your collaborator has modified the code but you have not

1. Repositories are both up to date
2. Dracula makes a change and pushes it to GitHub
3. Wolfman pulls down Dracula's change before making any changes
4. Wolfman will be asked to save a merge commit

GitHub

Merge #2

• You and your collaborator modify different lines of code
• Repositories are both up to date
• Wolfman makes a change to the last line of a file and pushes it to GitHub
• Dracula makes a change to the first line of the same file and tries to push it to GitHub (it fails)
• Dracula Pulls down Wolfman's changes, merging the changes locally
• Dracula will be asked to save a merge commit
• Dracula pushes merged changes to GitHub

GitHub

Dracula's local repositorymatch GitHub

Wolfman's local repository

does not match GitHub

Merge #3

• You and your collaborator modify the same line(s) of code
• Wolfman and Dracula both modify the last line of the file
• Wolfman pushes changes to GitHub
• Dracula commits changes and then pulls down Wolfman's changes
• Merge conflict

GitHub

Dracula's local repositorymatch GitHub

Wolfman's local repository

does not match GitHub

Merge #3: conflict

• You and your collaborator modify the same line(s) of code
• Wolfman and Dracula both modify the last line of the file
• Wolfman pushes changes to GitHub
• Dracula commits changes and then pulls down Wolfman's changes
• Merge conflict

Resolving Conflicts

• Dracula: open readme.md

• Dracula: edit readme.md to look like correct file
  • remove extra text
  • choose which lines you want to keep
  • Delete the <<<HEAD, =====, and >>> lines
• Dracula: save, add, commit, push
• Note: if you open this file in VS code, the git interface makes this really easy

Starting your collaboration

• We will divide you into breakout rooms with a partner
• Before you start, decide who will be Dracula and who will be Wolfman
• Follow the directions on the slides exactly
• Leave the breakout room if you need help, Professor Knox or myself will be checking in there 

Wolfman: Cloning a repository

• cd out of toy_repo, create a new directory called toy_repo_collab, and cd into it

• Clone Dracula's repository
•  
  • make sure its set to HTTPS
• cd into the toy_repo directory you just downloaded

Dracula: adding a collaborator

• Anyone can clone only collaborators can write
• Dracula only:
  • Click settings on the RHS
  • Click collaborators on the LHS
  • Add Wolfman's github username under collaborators

Wolfman: Accept Dracula's invitation

You should receive an email or notification on GitHub that you've been invited to join Dracula's repository. Accept this invitation

1. Dracula

• modify readme.md
• save your changes
• add and commit your changes
• push your changes to the remote repository

2. Wolfman

• pull down your partner's changes
  •  
• add a line to the end of the readme.md
• save your changes
• add and commit your changes
• push your changes to the remote repository

Collaborating

Merge without conflict

• Dracula: modify the first line of readme.md, save, add, and commit
• Wolfman: modify the last line of readme.md, save, add, and commit
• Dracula: pull down changes from Wolfman
  • you will be asked to save a merge commit message in nano
    • ctl+x
• Dracula: push your changes to the remote repository
• Wolfman: pull down changes from Dracula and save the commit message
• Wolfman: push your changes to the remote repository

Merge with conflicts

• Dracula: Before you pull down Wolfman's changes, edit the last line of the readme.md, save, add, and commit
• Dracula: try to pull down changes from the remote repository

Resolving Conflicts

• Dracula: open readme.md

• Dracula: edit readme.md to look like correct file
  • remove extra text
  • choose which lines you want to keep
  • Delete the <<<HEAD, =====, and >>> lines
• Dracula: save, add, commit, push

Exercise: Repeat for Wolfman

• Wolfman: pull down Dracula's changes
• Dracula: change the first line of hello_world.py
• Dracula: save, add, commit, push
• Wolfman: change the first line of hello_world.py, add, commit
• Wolfman: pull down Dracula's changes
  • you will get a conflict
  • open hello_world.py and edit to look like final version
  • save changes to hello_world.py
  • add, commit, push

Clone the course repository

• cd to your home directory (cd ~) or where ever you would like to put the repository
•