Incorporating Version Control into Programming Courses

Transcript

1. Incorporating Version Control into Programming Courses Tommy MacWilliam tmacwilliam@cs.harvard.edu
3. Source Control Management
4. What? • track revisions of files • review past versions of projects • collaborate with peers and staff
5. What? • CVS • SVN • Git • Mercurial • Bazaar • ...
6. Students: Why? • “I need to work on a project with a partner”
7. Students: Why? • “I need to work on a project with a partner” • “It was working a few hours ago, but I broke it”
8. Students: Why? • “I need to work on a project with a partner” • “It was working a few hours ago, but I broke it” • “I want to back up my code so I can work on another machine”
9. Staff: Why? • “I want to collect homework submissions on my server”
10. Staff: Why? • “I want to collect homework submissions on my server” • “I want to allow students to review each others’ code”
11. Staff: Why? • “I want to collect homework submissions on my server” • “I want to allow students to review each others’ code” • “I want to distribute updates to distribution code”
12. Vocabulary • repository: project containing source code files • commit: snapshot of a project in time • log: history of commits for a project • branch: independent set of changes • remote: server hosting code • tag: human-readable name for a commit
13. SCM Tools • centralized • all commits go to one repository • decentralized • commits go to developers’ individual repositories
14. SVN
15. SVN with Google Code
17. svn checkout https://project.googlecode.com/svn/trunk/ project --username you@gmail.com
18. Generated Password
19. https://code.google.com/hosting/settings
20. Repository Conventions • trunk: source code • branches: independent sets of changes • tags: named commits
21. svn add pset1.c
22. svn rm pset1.c
23. svn status
24. svn commit -m “done!”
25. svn update
26. svn log
27. Workflow • student creates and checks out repository • student adds, commits files to repository • staff updates from repository to view files
28. Basic SVN Workflow • create repository • svn checkout https://project.googlecode.com/svn/ • edit pset1.c • svn add pset1.c • svn commit -m “done!”
29. Practice! • create a new SVN repository called yourname-sigcse • checkout the repository to ~/svn/student1 • create a file called pset1.c • add and commit pset1.c to the pset1 repo • add and commit test.c to the pset1 repo • view the history of commits
30. svn diff
31. svn diff -r 1:2
32. Practice! • make changes to pset1.c without committing, then view the changes • commit the changes and compare to previous revision • compare the last revision to the first revision • search all commit logs for the word “done”
33. svn checkout -r 123
34. svn update -r 123
35. Practice! • roll back to the first revision • check out a new copy of pset1, starting at the second revision
36. SVN Collaboration • check out pset1 (again) to ~/svn/student2 • make a change and commit as student2 • update the repository as student1
37. Alice svnadmin create pset1 Bob
38. Alice svn co https://host/pset1 Bob
39. Alice svn co https://host/pset1 Bob
40. Alice svn co https://host/pset1 Bob
41. Alice svn co https://host/pset1 Bob
42. Alice svn commit -m “done” Bob
43. Alice svn commit -m “done” Bob
44. Alice svn up Bob
45. Alice svn up Bob
46. Merge Conflicts • students commit incompatible changes • cannot commit until conflicts are resolved
47. Creating a Merge Conflict • student1 edits pset1.c to say “here comes a conflict” • student1 commits to pset1 repo • student2 edits pset1.c to say “I don’t like conflict” • student2 tries to commit
48. Conflict discovered in '~/svn/student2/pset1/file.c'. Select: (p) postpone, (df) diff-full, (e) edit, (mc) mine-conflict, (tc) theirs-conflict, (s) show all options: d
49. Resolving a Merge Conflict • don’t panic! • mc: keep my changes to the file • tc: keep their changes to the file • e: manually edit conflicted file • p: view files that caused conflict separately
50. <<<<<<< this is student1 ======= this is student2 >>>>>>> Single File Resolution
51. jharvard@appliance (~/svn/student2/pset1): ls file.c file.c.mine file.c.r3 Multiple File Resolution
52. Resolving a Merge Conflict • don’t panic!
53. Practice! • edit student1/pset1.c to say “here comes a conflict” • commit from student1/pset1 • edit student2/pset1.c to say “I don’t like conflict” • commit from student2/pset1 • press “e” to edit as a single file • repeat, but press “p” to resolve conflict!
54. Tags • human-readable aliases for commits • software releases, betas, submissions
55. svn cp https://project.googlecode.com/svn/trunk/ https://project.googlecode.com/svn/tags/1.0
56. Branches
57. Branches • one partner wants to try something out
58. Branches • one partner wants to try something out • develop a feature independently of project
59. Branches • one partner wants to try something out • develop a feature independently of project • staff make changes during feedback process
60. svn cp https://project.googlecode.com/svn/trunk/ https://project.googlecode.com/svn/branches/test
61. Branches • independent sets of changes • changes on one branch don’t affect other branches • switching between branches changes working copy
62. svn switch https://project.googlecode.com/svn/branches/test
63. svn rm https://project.googlecode.com/svn/branches/test
64. Practice! • create a branch called “test” • switch to the branch • make changes and commit • switch back to trunk • delete branch “test”
65. SVN on GitHub
66. SVN on GitHub • svn co --depth empty https://github.com/you/project • svn up trunk • edit files, svn add, svn commit
67. Git
68. git config --global user.name “Tommy MacWilliam”
69. git config --global user.email tmacwilliam@cs.harvard.edu
70. git init
71. git add pset1.c
72. git add --all
73. git status
74. git commit -m “done!”
75. git log
76. 5aeebab117b892fa42002146e4c62be676bc4621 b43b0ad1e8108e7ab870d7a54feac93ae8b8600e 461476587780aa9fa5611ea6dc3912c146a91760 Commit ID
77. 5aeebab117b892fa42002146e4c62be676bc4621 b43b0ad1e8108e7ab870d7a54feac93ae8b8600e 461476587780aa9fa5611ea6dc3912c146a91760 Commit ID HEAD
78. Practice! • create a new repository in ~/git/pset1 • create a file called pset1.c • add and commit pset1.c • make more changes to pset1.c • add and commit pset1.c again
79. Git on GitHub
80. SSH Keys
81. ssh-keygen
83. git clone git@github.com:you/project
84. git remote
85. git remote add origin url
86. git push origin master
87. Basic Git Workflow • staff (or students) create remote repositories • students • clone repository • add and commit changes • push changes to remote repository
88. Practice! • create a GitHub repository • clone the repository • create pset1.c, then add and commit it • push pset1.c to the remote repository
89. git show
90. git show b43b0
91. git diff HEAD
92. git diff b43b0 5aeeb
93. Practice! • make changes to pset1.c without committing, then view the changes • commit the changes and compare to previous revision • compare the last revision to the first revision • search all commit logs for the word “done”
94. git checkout b43b0
95. git checkout b43b0 pset1.c
96. git checkout master
97. git reset --hard
98. Practice! • roll back to the first revision • roll only one file back to the second revision • fast-forward to the current state again
99. git revert b43b0
100. 5aeeb b43b0 46147
101. 5aeeb b43b0 46147 a45bc git revert 46147
102. Practice! • undo the changes in your last commit • undo the commit that undoes that commit
103. git tag done
104. git push --tags
105. git tag
106. git tag -l “1.*”
107. Practice! • create a tag called “1.0” • commit new changes • create a tag called “1.1” • view tags
108. git branch
109. git branch test
110. git checkout test
111. 5aeeb b43b0 46147 master
112. 5aeeb b43b0 46147 master f862f 36223 test git branch test
113. git checkout master
114. git merge
115. 5aeeb b43b0 46147 f862f 36223 git branch test a34bc git merge test
116. git branch -D test
117. Practice! • create a branch called “test” • switch to the test branch • make and commit changes • switch to the master branch • merge changes from the test branch • delete the test branch
118. 5aeeb b43b0 46147 f862f 36223 master test git branch test
119. 5aeeb b43b0 46147 f862f 36223 master git rebase
120. Practice! • create a branch called “test2” • switch to the test2 branch • make and commit changes • switch to the master branch • rebase changes from the test2 branch • delete the test2 branch
121. Collaborating with Git • students have their own local repositories • students commit, branch, etc. on local repositories • students push to and pull from a shared repository
122. git pull origin master
123. git pull --rebase
124. Alice Bob git init git add --all git commit
125. Alice git remote add origin url git push origin master Bob
126. Alice git remote add origin url git push origin master Bob
127. Alice git clone url Bob
128. Alice git clone url Bob
129. Alice git add --all git commit Bob
130. Alice git push origin master Bob
131. Alice Bob git push origin master
132. Alice git pull origin master Bob
133. Alice Bob git pull origin master
134. Practice! • create a pset2 repository on GitHub • clone the repository in ~/git/student1/pset2 • add, commit, and push a change • clone the repository in ~/git/student2/pset2 • add, commit, and push a change • pull the change from ~/git/student1/pset2
135. Merge Conflicts • don’t panic! • git status shows conflicted files • git add files to resolve conflicts
136. Resolving Conflicts <<<<<<< this is from test ======= this is from master >>>>>>>
137. Creating a Merge Conflict • student1 edits pset2.c to say “here comes a conflict” • student1 commits and pushes to pset2 repo • student2 edits pset2.c to say “I don’t like conflict” • student2 commits, tries to push
138. Resolving using Merge • fix conflicts • git add --all • git commit -m “merge”
139. Resolving using Rebase • fix conflicts • git add --all • git rebase --continue
140. Git on BitBucket
141. Using SCM in Programming Courses
142. Using Google Code • each student creates repository for each project • students add staff as collaborators
144. Using GitHub • https://github.com/edu • each student creates repository for each project • students add staff as collaborators
146. Using BitBucket • unlimited free private repositories! • same process as GitHub
147. Hosting SVN • svnadmin create --fs-type fsfs pset1 • repo/conf/svnserve.conf • svnserve
148. Hosting Git • https://github.com/sitaramc/gitolite • http://scie.nti.st/2007/11/14/hosting-git- repositories-the-easy-and-secure-way/
149. Repository-Based • each project is a separate repository • students collaborate on same hosted repository • if projects are totally separate, makes sense • if projects build on each other, makes less sense
150. Branch-Based • each student creates one repository for the course • each project is a different branch • if projects build on each other, makes sense • if projects are totally separate, makes less sense
151. Distributing Code • each student: • create repository on GitHub • git clone git://github.com/course/pset1.git • git remote rm origin • git remote add origin git@github.com/student/ pset1.git • git remote add distro git://github.com/course/ pset1.git
152. Submitting Code • students • git tag submission • git push --tags • staff • git checkout submission
153. When Disaster Strikes • svn revert --recursive . • git reset --hard
154. When Disaster Really Strikes • rm -rf .git • find . -type d -name .svn -exec rm -rf {} \;
155. Potential Pitfalls • merge conflicts prevent pushes! • don’t panic • one minute before the deadline, still don’t panic • distinguish between submission and version control? • have a backup submission plan!
156. Potential Pitfalls • commit timestamps are set by the client! • tags can be deleted and moved around • if new to SCM, submission process is very complicated • if using SCM, then teach SCM
157. Hooks • small scripts that are triggered by SCM events • post-receive: whenever a push is received
158. Automating Processes • http://developer.github.com/v3/ • https://confluence.atlassian.com/display/ BITBUCKET/Using+the+Bitbucket+REST +APIs
159. version50
160. gem install version50
161. v50 create
162. v50 status
163. v50 save
164. v50 history
165. v50 warp
166. v50 recover
167. v50 download
168. speakerdeck.com/tmacwill
169. Incorporating Version Control into Programming Courses Tommy MacWilliam tmacwilliam@cs.harvard.edu