source control

Source Control

Dr. Scott Schaefer

Version Control Systems

• Allow for maintenance and archiving of multiple versions of code / other files• Designed for text files… can be used with other

files, but some functionality won’t work

• Saves multiple copies of the same file

• Tracks changes to each file among multiple users

• Allows multiple users to edit the same file at the same time

Subversion

• Open-source version control system• Builds on CVS• Can handle local or remote repositories• Stores and transfers diffs of files… not

entire files (efficient)

ExampleRepository

User 1

User 2

X Z

Y

ExampleRepository

User 1

User 2

X Z

Y

add Xadd Yadd Z

ExampleRepository

User 1

User 2

X Z

Y

CommitX Z

Y1

ExampleRepository

User 1

User 2

X Z

Y

X Z

Y

Checkout

X Z

Y

1

ExampleRepository

User 1

User 2

X Z

Y

X Z

Y

Modify Y

X Z

Y

1

ExampleRepository

User 1

User 2

X Z

Y

X Z

Y

Commit

X Z

Y

X Z

Y

1

2

ExampleRepository

User 1

User 2

X Z

Y

X Z

Y

Update

X Z

Y

X Z

Y

1

2

ExampleRepository

User 1

User 2

X Z

Y

X Z

Y

Modify X

X Z

Y

X Z

Y

Modify X1

2

ExampleRepository

User 1

User 2

X Z

Y

X Z

Y

Commit

X Z

Y

X Z

Y

X Z

Y

1

2

3

ExampleRepository

User 1

User 2

X Z

Y

X Z

Y

Update

X Z

Y

X Z

Y

X Z

Y

merged text!

1

2

3

Another ExampleRepository

User 1

User 2

X

Y

X Z

Y

X Z

Y

1

Delete Z

Another ExampleRepository

User 1

User 2

X

Y

X Z

Y

X Z

Y

1

Commit

X

Y2

Another ExampleRepository

User 1

User 2

X

Y

X Z

Y

X

Y

1

Update

X

Y2

Conflicts

• Happen when you and someone else edit the same line of code

<<<<<<<<< .mine

Your change

=========

Someone else’s change

>>>>>>>>> .r 23

• Subversion keeps both your original (foo.mine) and the revision (foo.23)

Living with Version Control

• ALWAYS update before you commit changes

• If files change during the update, make sure everything works before you commit

• If you have a conflict, you MUST resolve the conflict before committing

• Update often to avoid conflicts

• Add descriptions to all of your commits

Your Project

• You MUST use version control for all of your projects

• I strongly suggest using Google Code as your SVN server• You can access it from anywhere