Git for the Android Developer

GitFor the Android DeveloperAnDevCon 2011 : Tony Hillerson#AnDevCon #effectiveuihttp://www.slideshare.net/thillerson/scm-for-android-developers-using-git

About Me• Worked with Android and Git for a few years now• O’Reilly Screencaster: Developing Android Applications • http://training.oreilly.com/androidapps/ • http://training.oreilly.com/androidapps2/• Tech Reviewer:

PreliminariesGetting Git and Getting Set Up

What’s a Git? A completely ignorant, childish person with no manners. - http://urbandictionary.com Linus Torvalds http://en.wikipedia.org/wiki/Linus_Torvalds

What’s a Git? Git is a free & open source, distributed version control system designed to handle everything from small to very large projects with speed and efficiency. - http://git-scm.com

Getting Set Up on Mac• Homebrew - http://mxcl.github.com/homebrew/• MacPorts - http://www.macports.org/

Getting Set Up on Windows• msysgit -http://code.google.com/p/msysgit/• Cygwin - http://www.cygwin.com/

Getting Set Up on Linux• apt, etc - you probably know the drill

Gooies!• Git Tower - http://git-tower.com M• Brother Bard’s GitX fork -Mac http://brotherbard.com/blog/2010/03/experimental-gitx-fork/ A C• Tortoise Git - http://code.google.com/p/tortoisegit/ WMac I N

Eclipse Integration• http://www.eclipse.org/egit/

Reference• Git - http://git-scm.com/• ProGit - http://progit.org/book/ - Scott Chacon• Insider Guide to Github - http://www.pragprog.com/screencasts/ v-scgithub/insider-guide-to-github - Scott Chacon

Note• Code may be in backticks: `git <command>` • Don’t input the backticks

The Command LineA Short Sermon

Seven Use CasesWhere Git will Make your Life Easier

Project HistoryGit will Make your Life Easier

Why Source Control• For the solo developer? • Protection against mistakes • Freedom • to refactor • to experiment• For the development team? • All of the above, plus: • Parallel development • Merging different code branches

Simple Commands• `git init`- Creates an empty Git repository• .gitignore - tells git to ignore certain files• `git add` - Adds a file to the stage (“stages a file”)• `git rm` - Removes from version control• `git commit` - Commits the staged changes to the (local) repository• `git log`• `git add -i` Interactive Add

git git or cloneinit git 86650c185eda50c9f9d58e2fbdf8b7113e5dee54 git commit changes add git git commit 6facfd9f34173f4fb024196996e948a87c85eb56 changes add git git commit b02ef5bf190e28ba24eab3ffab6133181cb5b5ef changes add ... ∞Simple Workﬂow

.gitignore• Can be nested deeply• https://github.com/github/gitignore • Use it! Contribute!

Git Log - The Project’s History• What got committed?• Commit messages• Content• When? Who?

What’s With all the Characters?86650c185eda50c9f9d58e2fbdf8b7113e5dee54• SHA1 Hash• Uniquely identiﬁes a commit• Secure - very unlikely that someone can tamper with content in a repository “... to have a probability of a SHA1-hash collision rise to 1/2, you need about 10^24 objects ...” - Scott Chacon in Pro Git (paraphrased)

Interactive Add - Building Commits• `git add` simply adds to the stage• `git commit -a` will commit all changes to tracked ﬁles (add and commit)• `git add -i` -- a command line tool to interactively add changes• Individual commits shouldn’t leave things broken• Try to commit some useful feature or bug ﬁx all together

Getting Out of TroubleGit will Make your Life Easier

Advanced Commands• blame• checkout• commit -a• reset• stash• commit --amend• revert

git blame• remember: git help blame• Who broke the build??? etc...

git checkout, commit -a, reset• remember: git help reset• `git commit -a` = commit bypassing `git add`• `git checkout <filename>` = remove all unstaged changes• `git reset <filename>` = opposite of `git add <filename>`• `git reset HEAD` = same as above - acts on all changes• `git reset HEAD^` (also ^^, or ~1, ~42, etc.) = rollback commits to working tree• `git reset --soft` = rollback commit to stage

git stash• remember: git help stash• Stash away changes in a safe place

git commit --amend• Oops! I misspelled something in the commit message• Oops! I did `git commit -a` and forgot to `git add` a ﬁle• Oops! I just committed a bug• USE ONLY BEFORE YOU SHARE CHANGES

git revert• Commits the reverse of a commit• The previous commit is still there• != svn revert

CollaborationGit will Make your Life Easier

Remotes• remote add• push• clone• pull• fetch

Strategies• Star• Peer to Peer• Blessed Repository• Hierarchical

Committer Committer Committer “The Committer Server” Committer CommitterStar

• ssh://user@computer:path/to/repo.git• http Peer• Gitosis• Gitolite Peer PeerPeer to N Peers

Dictator ... etc. Maintains a “blessed repository” Lieutenant LieutenantDeveloper Developer Developer DeveloperHierarchical (Linux model)

Topical DevelopmentGit will Make your Life Easier

Branching• checkout -b• merging• Rebasing• cherry-pick

How To Think About Branching• Topic Branches• Mainline • What do you want “master” to mean?• Branching examples

Topic Branches• Branching is about controlling feature sets• Make a new branch for a story• Make a new branch for a bug ﬁx• Make a new branch to spike something

Team Branching Strategies• What do you want “master” to mean?• Keep master deployable? • one strategy for web software• Use “master” as an integration branch? • Each developer uses topic branches and integrates to master • Make a branch for releases

Branching git checkout -b add_login_activitymasterMac fb4f5d9 c5083fa add_login_activity Mac 9aa8827 fe594ce ccb6f5e

Branching: Merging git checkout master git merge add_login_activitymasterMac 9aa8827 fe594ce ccb6f5e fb4f5d9 c5083fa 3f43fa3 add_login_activity Mac 9aa8827 fe594ce ccb6f5e

Branching: Rebasing master Mac fb4f5d9 c5083fa 3f43fa3 add_login_activity before Mac 9aa8827 fe594ce ccb6f5emasterMac fb4f5d9 c5083fa 3f43fa3 add_login_activit after Mac 9aa8827 fe594ce ccb6f5e `git rebase master`

Branching: Rebasing• Better than merging• Don’t use if you’ve pushed your branch to a remote • Git will complain about refs • Can override with `git push -force`• Also available on `git pull --rebase` • Helpful for avoiding merge commits • May cause problems if git can’t automatically merge • `git reset HEAD` and start over with normal `git pull`

Cherry-pick git cherry-pick fe594ce A new commitmaster with the changes from fe594ceMac fb4f5d9 c5083fa 3f43fa3 add_login_activity Mac 9aa8827 fe594ce ccb6f5e

Cherry Picking• Doesn’t add a reference to the old commit• Only applies the changes• Future merges should apply cleanly

Release ManagementGit will Make your Life Easier

Tagging• tag• push --tags

Tagging git tag -a -m"Tagging v1.0" v1.0 c5083famasterMac fb4f5d9 c5083fa 3f43fa3• Both -v1.0 and c5083fa will point to c5083fa• Push this tag with `git push --tags`• Can be cryptologically signed

Bug FixingGit will Make your Life Easier

Bug Fixing• blame• bisect

Bisect git bisect start HEAD git bisect bad fb4f5d9 Mac c5083fa 3f43fa3 9aa8827 fe594ce ccb6f5e 2e531cb git bisect good fb4f5d9 HEAD fb4f5d9 Mac c5083fa 3f43fa3 9aa8827 fe594ce ccb6f5e 2e531cb git bisect good Git tells you this was the git bisect good ﬁrst bad git bisect bad commit HEAD fb4f5d9 Mac c5083fa 3f43fa3 9aa8827 fe594ce ccb6f5e 2e531cb

Open Source CodeGit will Make your Life Easier

Github.com• Search it!• Forking• Pull Requests

Thank you!GitFor the Android DeveloperAnDevCon 2011 : Tony Hillerson

Git for the Android Developer

by EffectiveUI on Nov 02, 2011

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Git for the Android Developer Presentation Transcript