Practical Git(Hub)

Git basics, best practices, tips & tricks. Talk given to my teammates at Kerad Games.

Transcript

1. Practical Git(Hub)
   

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2. Git basics
   Best practices
   Rebase & you
   Tips & tricks
   

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3. ❝ git gets easier once you
   get the basic idea that
   branches are
   homeomorphic
   endofunctors mapping
   submanifolds of a Hilbert
   space ❞
   -- The Internet
   

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4. ❝ SourceTree sucks ❞
   -- Me
   

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5. Git basics
   

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6. Git is…
   …a distributed revision control and source code
   management system.
   … not an evolution of SVN.
   … not easy.
   

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7. add
   am
   apply
   archimport
   archive
   bisect
   blame
   branch
   bundle
   cat-file
   check-attr
   check-ignore
   check-mailmap
   check-ref-
   format
   checkout
   checkout-
   index
   cherry
   cherry-pick
   citool
   clean
   clone
   commit
   commit-tree
   config
   count-objects
   cvsexportcomm
   it
   cvsimport
   cvsserver
   daemon
   describe
   diff
   diff-files
   diff-index
   diff-tree
   difftool
   fast-export
   fast-import
   fetch
   fetch-pack
   filter-branch
   fmt-merge-msg
   for-each-ref
   format-patch
   fsck
   gc
   get-tar-
   commit-id
   grep
   gui
   hash-object
   help
   http-backend
   http-fetch
   http-push
   imap-send
   index-pack
   init
   instaweb
   log
   ls-files
   ls-remote
   ls-tree
   mailinfo
   mailsplit
   merge
   merge-base
   merge-file
   merge-index
   merge-one-
   file
   merge-tree
   mergetool
   mktag
   mktree
   mv
   name-rev
   notes
   pack-objects
   pack-
   redundant
   pack-refs
   parse-remote
   patch-id
   prune
   prune-packed
   pull
   push
   quiltimport
   read-tree
   rebase
   receive-pack
   reflog
   relink
   remote
   repack
   replace
   request-pull
   rerere
   reset
   rev-list
   rev-parse
   revert
   rm
   send-email
   send-pack
   shell
   shortlog
   show
   show-branch
   show-index
   show-ref
   stash
   status
   stripspace
   submodule
   svn
   symbolic-ref
   tag
   unpack-file
   unpack-
   objects
   update-index
   update-ref
   update-
   server-info
   upload-
   archive
   upload-pack
   var
   verify-pack
   verify-tag
   whatchanged
   write-tree
   

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8. add
   am
   apply
   archimport
   archive
   bisect
   blame
   branch
   bundle
   cat-file
   check-attr
   check-ignore
   check-mailmap
   check-ref-
   format
   checkout
   checkout-
   index
   cherry
   cherry-pick
   citool
   clean
   clone
   commit
   commit-tree
   config
   count-objects
   cvsexportcomm
   it
   cvsimport
   cvsserver
   daemon
   describe
   diff
   diff-files
   diff-index
   diff-tree
   difftool
   fast-export
   fast-import
   fetch
   fetch-pack
   filter-branch
   fmt-merge-msg
   for-each-ref
   format-patch
   fsck
   gc
   get-tar-
   commit-id
   grep
   gui
   hash-object
   help
   http-backend
   http-fetch
   http-push
   imap-send
   index-pack
   init
   instaweb
   log
   ls-files
   ls-remote
   ls-tree
   mailinfo
   mailsplit
   merge
   merge-base
   merge-file
   merge-index
   merge-one-
   file
   merge-tree
   mergetool
   mktag
   mktree
   mv
   name-rev
   notes
   pack-objects
   pack-
   redundant
   pack-refs
   parse-remote
   patch-id
   prune
   prune-packed
   pull
   push
   quiltimport
   read-tree
   rebase
   receive-pack
   reflog
   relink
   remote
   repack
   replace
   request-pull
   rerere
   reset
   rev-list
   rev-parse
   revert
   rm
   send-email
   send-pack
   shell
   shortlog
   show
   show-branch
   show-index
   show-ref
   stash
   status
   stripspace
   submodule
   svn
   symbolic-ref
   tag
   unpack-file
   unpack-
   objects
   update-index
   update-ref
   update-
   server-info
   upload-
   archive
   upload-pack
   var
   verify-pack
   verify-tag
   whatchanged
   write-tree
   

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9. Making changes
   …or how add, commit, checkout works
   HEAD Index Working
   Directory
   checkout
   add
   commit reset
   

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10. Grouping changes
    …or how to use branches via checkout, branch, merge
    A
    develop HEAD
    

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11. Grouping changes
    …or how to use branches via checkout, branch, merge
    A
    develop
    feature
    HEAD
    git branch feature
    

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12. Grouping changes
    …or how to use branches via checkout, branch, merge
    A
    develop
    feature HEAD
    git branch feature
    git checkout feature
    

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13. Grouping changes
    …or how to use branches via checkout, branch, merge
    A
    develop
    feature HEAD
    git branch feature
    git checkout feature
    git add & git commit
    B
    

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14. Grouping changes
    …or how to use branches via checkout, branch, merge
    A
    develop
    feature HEAD
    git branch feature
    git checkout feature
    git add & git commit
    git add & git commit
    B C
    

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15. Grouping changes
    …or how to use branches via checkout, branch, merge
    A
    develop
    feature HEAD
    git branch feature
    git checkout feature
    git add & git commit
    git add & git commit
    …
    B C
    D E
    

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16. Grouping changes
    …or how to use branches via checkout, branch, merge
    A
    develop
    feature
    HEAD
    git branch feature
    git checkout feature
    git add & git commit
    git add & git commit
    …
    git checkout develop
    B C
    D E
    

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17. Grouping changes
    …or how to use branches via checkout, branch, merge
    A
    develop
    feature
    HEAD
    git branch feature
    git checkout feature
    git add & git commit
    git add & git commit
    …
    git checkout develop
    git merge feature
    B C
    D E F
    

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18. Best practices
    Good
    

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19. commit
    commit often
    write good commit messages
    do not commit unrelated
    changes together
    

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20. commit
    commit often
    write good commit messages
    do not commit unrelated
    changes together
    

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21. branches
    anything in master is deployable
    anything in develop will be delivered
    in the next release *
    feature-branches is where
    we should commit
    

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22. branches
    anything in master is deployable
    anything in develop will be delivered
    in the next release
    feature-branches is where
    we should commit
    

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23. branches
    It’s ok to have different branch schemes, depends
    on client, project, technology…
    a common workflow > no workflow at all
    keep it simple or people won’t follow the scheme
    

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24. .gitignore
    know and use .gitignore
    committed files cannot be ignored (well, not easily)
    https://github.com/github/gitignore
    take a look at git config and .gitattributes as well
    

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25. git pull
    God kills a kitten
    every time you do this:
    Merge branch 'foobar' of github.com:keradgames/goldenmanager-ios
    into foobar
    

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26. git pull
    git pull is considered harmful
    git fetch origin
    git rebase origin/develop
    git config --global pull.ff only
    when changes can’t be applied fast-forward:
    

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27. git pull
    do it for the kittens
    if you need to solve conflicts when pulling, you are
    doing something wrong
    

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29. pull request
    why?
    we all make errors
    find logic bugs
    high quality code
    enforce readable code style
    enforce good commit history
    let people know what you are
    working on (even discuss future
    features)
    learn (both ways)
    fun
    

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30. pull request
    useful messages:
    “Can we make this more readable?”
    “What would be a better name for this method?”
    “This needs to be refactored into smaller methods”
    “Why did you choose this approach?”
    “”
    

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31. Rebase & you
    

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32. Historical revisionism
    A B C
    D E
    develop
    feature
    

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33. Historical revisionism
    A B C
    D E
    develop
    feature
    git checkout feature
    git rebase develop
    

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34. Historical revisionism
    A B C
    D E D’
    develop
    feature
    rebasing (1/2)
    

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35. Historical revisionism
    A B C
    D E D’ E’
    develop
    feature
    rebasing (2/2)
    

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36. Historical revisionism
    A B C
    D E D’ E’
    develop
    feature
    rebasing done!
    

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37. Historical revisionism
    A B C
    D E D’
    develop
    feature
    git rebase -i develop
    

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38. Historical revisionism
    A B C
    D E E’
    develop
    feature
    git rebase -i develop
    

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39. Historical revisionism
    A B C
    D E E’ D’
    develop
    feature
    git rebase -i develop
    

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40. © http://www.maneobjective.com/2013/10/danger-controversial-ingredients-in.html
    

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41. Rebasing dangers
    … or when not to use rebase.
    Don’t rebase public history.
    Think before rebasing long & old branches.
    

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42. Tips & tricks
    

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43. How do I…
    …find the commit that broke my project?
    git bisect start
    git bisect bad
    git bisect good
    # Bisecting: N revisions left to test after this
    (roughly log2(N) steps)
    git bisect run
    

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44. How do I…
    …save current changes for later use without committing
    because you need to do something else?
    git stash
    git stash list
    git stash pop
    git stash apply
    

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45. How do I…
    …revert a non-staged change?
    git checkout -- path/to/file/to/revert
    git checkout -- .
    …revert all non-staged changes (and nothing else)?
    ⚠
    ⚠
    

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46. How do I…
    …revert a staged change?
    git reset path/to/file/to/revert
    git reset
    …revert all staged changes (and nothing else)?
    

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47. How do I…
    …revert all staged and non-staged changes?
    (i.e.: all non-committed changes)
    git reset --hard
    ⚠
    

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48. How do I…
    …revert the last non-pushed commit?
    git reset HEAD^
    …revert/modify a previous non-pushed commit?
    git rebase -i
    

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49. How do I…
    …revert a pushed/public change?
    git revert
    

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50. How do I…
    …copy an existing commit (from another branch or
    another point in history) ?
    git cherry-pick
    

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51. How do I…
    …split changes in a single file into multiple commits?
    git add -p
    # for each hunk: y, n, s, e …
    git add -i
    

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52. How do I…
    …clean remote branches?
    git remote prune origin
    git config --global remote.origin.prune true
    git push origin --delete
    …delete a remote branch?
    

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53. How do I…
    … remove untracked files and directories?
    git clean -d -f
    ⚠
    

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54. How do I…
    … see changes introduced by a commit?
    git show
    … see changes introduced by a merge commit?
    git show -m
    

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55. How do I…
    … find who fucked up modified lines 42 to 84 of this file?
    git blame -L 42,84 path/to/file
    

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56. Questions?
    

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57. Thanks!
    

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