Version control 101

transcript

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

Why Version Control?

• To work on something• Without hindering others• Try, fail and start over• Distribute workload

• 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)

• 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

Common situa>on

Branches Discontinued

• Is the most up-‐to-‐date lifeline• All branches start from here• All branches must return here

Basic merging & tagging

• Branch from TRUNK• Work on branch• Integrate branch• Tag event

Standard Layout

• Repository-‐ trunk: the main lifeline of sources

-‐ branches: your playground

-‐ tags: your memory labels

Crea>ng a branch

Branch

How to branch

• svn cp ^/trunk ^/branches/myBranch• svn co ^/branches/myBranch

Keep in sync

Branch

How to sync

• svn merge ^/repo/trunk• svn commit

Integra>ng a branch

Branch

How to integrate

• svn merge -‐-‐reintegrate ^/branches/myBranch

• svn commit

Tagging

Branch

How to tag

• svn cp ^/repo/trunk@12345 ^/tags/myTag

Sub-‐branching

• Why sub-‐branching?• New branch• Small sub-‐branches• Integrate back

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

Create a sub-‐branch

Branch

Sub-branch

Same way as creating a branch!

How to sub-‐branch

• svn cp ^/repo/branches/myBranch^/repo/branches/mySubBranch

Syncing sub-‐branches

Branch

Sub-branch

How to sync sub branches

• svn merge ^/repo/trunk ^/repo/branches/myBranch

• svn merge ^/repo/branches/myBranch^/repo/branches/mySubBranches

Reintegrate sub-‐branch

Branch

Sub-branch

How to reintegrate sub-‐branch

• svn merge -‐-‐reintegrate ^/repo/branches/mySubBranch^/repo/branches/myBranch

Reintegrate = End-‐Of-‐Life

Complex situa>ons

• 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

Visualiza>on complex situa>on

Feature branch

Iteration branch Iteration branch

Task branches

XNew release

XHot fixes

Remember

• 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

//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

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!

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

Version control 101

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