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Version Control 101 How to master SCM with Subversion
| Date post: | 29-Jan-2015 |
| Category: |
Technology |
| Upload: | michelangelo-van-dam |
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Version Control 101
How to master SCM with Subversion
What is Version Control?
• Maintain versions of sources• Allows for collabora>on• Tracking progress• Recording history
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Why Version Control?
• To work on something• Without hindering others• Try, fail and start over• Distribute workload
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Lingo
• Repository: the loca>on that acts as Version Control system
• Trunk: the lifeline of the project where everything starts and everything ends
• Branch: a custom lifeline for individual tasks or collec>ve works
• Tag: a label to iden>fy something in >me (like a version or milestone)
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• Branching: the act of crea>ng a side lifeline for a specific purpose
• Tagging: the act of labeling an event in >me•Merging: the act of synchronizing a side lifeline with his parent lifeline
• Integra6ng: the act of reuni>ng the side lifeline with its paren lifeline
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Common situa>on
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Trunk
Tags
Branches Discontinued
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Trunk
• Is the most up-‐to-‐date lifeline• All branches start from here• All branches must return here
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Basic merging & tagging
• Branch from TRUNK• Work on branch• Integrate branch• Tag event
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Standard Layout
• Repository-‐ trunk: the main lifeline of sources
-‐ branches: your playground
-‐ tags: your memory labels
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Trunk
Trunk
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Crea>ng a branch
Trunk
Branch
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How to branch
• svn cp ^/trunk ^/branches/myBranch• svn co ^/branches/myBranch
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Keep in sync
Trunk
Branch
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How to sync
• svn merge ^/repo/trunk• svn commit
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Integra>ng a branch
Trunk
Branch
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How to integrate
• svn merge -‐-‐reintegrate ^/branches/myBranch
• svn commit
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Tagging
Trunk
Branch
Tag
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How to tag
• svn cp ^/repo/trunk@12345 ^/tags/myTag
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Sub-‐branching
• Why sub-‐branching?• New branch• Small sub-‐branches• Integrate back
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Why sub-‐branching?
• Working on a large task-‐ With several dependent sub-‐tasks
• You want to keep related sources together-‐ O^en when doing versioning
• Try stuff out
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Create a sub-‐branch
Trunk
Branch
Sub-branch
Same way as creating a branch!
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How to sub-‐branch
• svn cp ^/repo/branches/myBranch^/repo/branches/mySubBranch
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Syncing sub-‐branches
Trunk
Branch
Sub-branch
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How to sync sub branches
• svn merge ^/repo/trunk ^/repo/branches/myBranch
• svn merge ^/repo/branches/myBranch^/repo/branches/mySubBranches
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Reintegrate sub-‐branch
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Trunk
Branch
Sub-branch
How to reintegrate sub-‐branch
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• svn merge -‐-‐reintegrate ^/repo/branches/mySubBranch^/repo/branches/myBranch
Reintegrate = End-‐Of-‐Life
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Complex situa>ons
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• A project with mul>ple tasks• A project with mul>ple developers
Handle complex situa>ons
• Create a new branch for the project-‐ This will be your own trunk
-‐ Keep it in sync with TRUNK
• For each itera>on create a sub-‐branch-‐ This will be your working branch
-‐ Keep it in sync with project branch
• For each task create a sub-‐branch from the sub-‐branch-‐ This will be your feature branch (playground)
-‐ Keep it in sync with project sub-‐branch
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Visualiza>on complex situa>on
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Trunk
Feature branch
Iteration branch Iteration branch
Task branches
XNew release
Merge
Merge
Merge
XHot fixes
Merge
Merge
Merge
Remember
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• Always keep in sync with parent branch• Merge down one step at a >me
What about conflicts
• Conflicts indicate a problem-‐ Code changed on same posi>on
• What’s “working”, “le^” and “right”?-‐ Working is the current situa>on a^er merge with your code
-‐ Base or le^ is the code before merge
-‐ Head or right is incoming changes from the code you merge with
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//File: example.php<<<<<<.working $this->property = $newValue;====== $this->property = $oldValue;>>>>>>.r12345-right
Example conflict
• By opening the conflicted file-‐ look what’s in conflict
-‐ discuss with developers which value to take
-‐ if both changes are required, you need add both
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Don’t solve conflicts yourself!Always consult with all developers involved!
Changes made by one developer conflicting other developer’s changes might require both changes to be implemented!
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Some advice
• Commit smallEnsure your commit contains one task
• Commit o=enMore commits build up history, allowing to replay changes you made easily to parent
• Integrate quickDon’t keep sub-‐branches alive too long, the sooner they are reintegrated, the easier it is to merge with other tasks
Recommended Reading
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Click on the books to order
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