So Help Me God, You Will Understand Git's Model, Even If It Kills Me

Transcript

1. Go drink.
   Presentation starts at
   6pm.
   

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2. 1
   2 3
   4
   6
   7 8
   9 11 15 16
   10 12 14
   5 13
   Trunk
   Branches
   Merges
   Tags
   Discontinued
   development branch
   

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3. Everyone Has A Fork
   • Offline
   • No server necessary
   • Frequent branching and merging
   

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5. So Help Me God,
   You Will Understand Git’s
   Model
   Even If It Kills Me
   

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6. SHA1
   $ echo 'HELLO TWU' | shasum
   7068de75a45caca38a6d772d4b0f371bda003256 -
   

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7. Git Object Model
   •K: SHA(data)
   •V: data
   

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8. Objects
   •Type
   •Size
   •Content
   

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9. Blobs
   Trees
   Commits
   Refs
   Tags
   

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10. Blobs
    $ git cat-file -p 1377554ebea6f98a2c748183bc5a96852af12ac2
    *.swp
    

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11. Trees
    $ git ls-tree eebc19d60284277eba86620ec828d73d0cdf822a
    100644 blob 1377554ebea6f98a2c748183bc5a96852af12ac2 .gitignore
    100644 blob ac1bfdc65a699792310498fc0ba003e61eddf1d0 bad.lua
    100644 blob b2f5ce962808f4edd04336eb803b6445b843e052 boom.lua
    100644 blob 6b1c0b8946e40ff393f73d80a885fdd39fba93dd bullet.lua
    100644 blob 268a04ca259b566c7340d8ba8dab8ce0590e8352 main.lua
    100644 blob 67638336f18030013b0bcc7533987a6ba892ba46 rail.lua
    040000 tree 415ee50b6cf27815df2750de33b0eac1df8ad814 resources
    100644 blob c1a79a49a98c0b3868e33270465121cf40dc622e ship.lua
    100644 blob d77c7f1d5fecfc6c998e2eec628495075ba27ec1 wave.lua
    

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12. Commit
    •Tree
    •Parent(s)
    •Author and Committer
    •Message
    

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13. Commit
    $ git cat-file -p eea6bd6db666365b33496b9fc4c2d55c7af8fdcd
    tree eebc19d60284277eba86620ec828d73d0cdf822a
    parent bfe1204bb4d8eaa00b7a20c47e6e421e9be25322
    author Sam Gibson 1327417487 +0530
    committer Sam Gibson 1327417487 +0530
    Bounds -> Box
    

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14. Tags
    •Annotated
    •Lightweight
    

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15. Annotated Tag
    •Object SHA1
    •Type
    •Tagger
    •Message
    

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16. Refs
    (lightweight tags)
    •Branches (local and remote)
    •Heads
    •Tags
    

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17. INCOMING
    COPYRIGHT
    VIOLATION
    

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18. In Summary
    http://book.git-scm.com/1_the_git_object_model.html
    

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19. Let’s Play A Game
    “What Happens?”
    

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20. What Happens?
    $ git init
    Initialized empty Git repository in /.git/
    

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21. Yes, that was a warm up
    $ find ./.git
    .
    ./.git
    ./.git/config
    ./.git/description
    ./.git/HEAD
    ./.git/hooks
    ...
    ./.git/info/exclude
    ./.git/objects/info
    ./.git/objects/pack
    ./.git/refs/heads
    ./.git/refs/tags
    

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22. What Happens?
    $ touch xyzzy
    $ git add xyzzy
    $ git status
    # On branch master
    #
    # Initial commit
    #
    # Changes to be committed:
    # (use "git rm --cached ..." to unstage)
    #
    # new file: xyzzy
    #
    

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23. The Index
    •Cache
    •Staging
    •Whitelist?!
    

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24. You Delete A File And
    Then Commit It?
    $ rm xyzzy
    $ git commit -m 'What happens?'
    

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25. You Can’t Explain That!
    $ ls
    $ git status
    # On branch master
    # Changes not staged for commit:
    # (use "git add/rm ..." to update what will be committed)
    # (use "git checkout -- ..." to discard changes in
    working directory)
    #
    # deleted: xyzzy
    #
    no changes added to commit (use "git add" and/or "git commit -a")
    $ git checkout -- xyzzy
    $ ls
    xyzzy
    

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26. Reflogs
    $ git reflog
    add17aa HEAD@{0}: commit: NO
    a1b7f8d HEAD@{1}: commit (initial): What happens?
    

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27. Practical Examples
    whereupon mayhap we conversate
    

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28. Fetch
    Imports remote refs
    and their associated objects
    

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29. 3-Way Merge
    • "your" commit
    • "their" commit
    • their most recent ancestor
    

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30. Rebase
    • "your" commit
    • "their" base commit
    • their most recent ancestor
    • Replays each of “your” differences
    upon “their” base
    

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31. Stash Working
    Directory
    Index
    HEAD
    

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32. fin
    

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33. Git Community Book
    http://book.git-scm.com
    

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