The Git Historian

Your git repository’s log wants to tell you a story, with valuable clues about how your software became the thing of beauty (or horrible mess) that it is today. You just need to know how and where to look. In this talk, we’ll dig into a project’s history to learn how it evolved, using only the git command line utility to search through commits–no extra software required! To close, we’ll discuss how to leave good clues for future historians.

Transcript

1. The Git Historian Aaron Sumner
3. Disclaimers • Mileage may vary • You probably know something I don’t! • Links to slides and references at the end
4. Based on a true story.
5. for development with backup from Webrick" $n=Module.new{extend Rack;a,D,S,q=Rack::Builder.new,Object.method(: define_method),/@@ *([^\n]+)\n(((?!@@) [^\n]*\n)*)/m %w[get post put delete].map{|m|D.(m){|u,&b| a.map(u){run->(e){[200,{"Content-Type"=>"text/ html"},[a.instance_eval(&b)]]}}}} Tilt.mappings.map{|k,v|D.(k){|n,*o|$t|| =(h=$u._jisx0301("hash, please");File.read(caller[0][/^[^:] +/]).scan(S){|a,b|h[a]=b};h);v[0].new(*o) {n=="#{n}"?n:$t[n.to_s]}.render(a,o[0].try(: [],:locals)||{})}} %w[set enable disable configure helpers use register].map{|m|D.(m){|*_,&b|b.try : []}};END{Rack::Handler.get("webrick").run(a,Po rt:$z){|s|$r=s}} !
6. git blame lib/framework.rb
7. 55a43a7 Fix some stuff "
10. #
11. commit 55a43a73b1f7be5f410f81e58ec1df24a1792bd5 Author: Aaron Sumner <aaron@example.com> Date: Mon Mar 20 19:32:25 2017 -0500 Fix some stuff $
12. What went wrong?
13. % %
14. %
15. What’s the story?
16. The Git Historian & '
17. Digging through history '
18. thoughtbot/clearance
19. git blame file git show SHA
25. git log
44. Useful flags for git log git log --reverse git log --oneline git log --patch (-p) git log -p path/to/file git log -p -S term git log --grep term git log --stat man git-log
45. Pager (less -S)
54. Searching git log /pattern ?pattern n for next instance N for previous instance j/k one line down/up gg beginning of output G end of output /^commit man less
55. Leaving a trail &
56. Atomic commits
57. git add -am “fix it” %
58. git add -p git commit (
66. Tips for a clean commit • Include the code, corresponding documentation, and corresponding test coverage • Separate out refactoring that could obfuscate the feature change • Keep other corrections in separate commits
67. “The seven rules of a great commit message” 1. Separate subject from body with a blank line 2. Limit the subject line to 50 characters 3. Capitalize the subject line 4. Do not end the subject line with a period 5. Use the imperative mood in the subject line 6. Wrap the body at 72 characters 7. Use the body to explain what and why vs. how
68. Rebasing
69. ☠
70. git rebase commit git rebase branch git rebase tag
71. git rebase --interactive commit
72. git rebase --interactive --autosquash commit
98. git rebase --interactive --autosquash git commit --fixup sha git commit --squash sha -m “Additional information.”
99. Summary
100. ' git blame git show git log
101. git add -p git rebase good messages! &
102. speakerdeck.com/ruralocity www.aaronsumner.com
103. References • https://everydayrails.com/2017/01/02/git-command-line-log-search.html • http://tbaggery.com/2008/04/19/a-note-about-git-commit-messages.html • https://chris.beams.io/posts/git-commit/ • http://johnkary.net/blog/git-add-p-the-most-powerful-git-feature-youre-not- using-yet/ • https://technosorcery.net/blog/2010/02/fun-with-the-upcoming-1-7-release-of- git-rebase-interactive-autosquash/ • https://github.com/rkh/almost-sinatra • https://github.com/thoughtbot/clearance • http://emojipedia.org/