What is version control? Why use it? How do I use it?

See the lecture notes, but briefly:

• Version control lets you maintain successive versions of the software (and associated documents) that you develop

• Version control helps you:
  • Try out ideas and (as needed) revert to previous ideas
  • Combine the efforts of a team of software engineers

• To use version control, you:
  1. Checkout your project from the repository to your laptop

     • Your repository is on a machine in the basement of Crapo, in the AFS folder:

            /class/csse/csse120/turnin/sectionBLAH/YourUsername/cvshome
       

       where BLAH is your section number and YourUsername is your own username

     • When you work with a partner, you will use your repository or your partner's (but not both)

     • Checking out the project copies it from the repository to your laptop

     • The repository will hold many projects (like JavaEyes, WordGames, etc), each of which is called a module

     • Sometimes we put the first version of the project into the repository, sometimes you will do so

  2. Work on the project on your laptop

  3. Checkin your project from your laptop to the repository
     • In our system, checkin involves four steps:
       • Update to determine how your local copy now differs from the repository
       • Add contents to add any new files that you created to your project
       • Commit to copy the changes to your project back to the repository
       • (sometimes) Tag the version to give the version a name (like Stage1, Stage2, etc)

Checkin a project as follows:

This example uses the JavaEyes project; do other projects in a similar fashion, just changing the Module.

1. Update:
   • What this does:
     • This determines how your local copy now differs from the repository.
     • Also, if your partner made any changes to the repository that conflict with the changes that you made, CVS attempts to resolve the conflicts.
   • How to do it:
     • Right-click on your JavaEyes folder
     • Select CVS Update
     • Look at the output and ask questions about it as necessary.
       • If the repository had changed (because a teammate was working on it concurrently, for example) then CVS will attempt to resolve the conflicts. If it cannot, it will ask your help. Usually, no conflicts will occur.
       • After update, CVS shows you which files are modified by displying their icons in red (not green)

2. Add contents:
   • What this does:
     • This adds any new files that you created to your project
   • How to do it:
     • Right-click on your JavaEyes folder
     • Select CVS Add Contents
     • Look at the output and ask questions about it as necessary.
       • CVS marks new files, if any, by a question mark.
       • After add contents, those files become red (like the other modified files ready to be committed to the repository)

3. Commit:
   • What this does:
     • This copies changes that you made in your local copy on your laptop back to the repository
   • How to do it:
     • Right-click on your JavaEyes folder
     • Select CVS Commit
     • Type a meaningful comment (e.g., "Version in the middle of Stage 1" or "Version after Stage 3") where it asks for one
     • Look at the output and ask questions about it as necessary.
       • After commit, CVS changes the modified (red) files to green icons
       • You can always roll back to any version that you committed.

4. Tag:
   • What this does:
     • This tags the version with a name (of your choosing), which makes it easy to checkout that version.
     • The tags are important because we use such names to know what versions to grade!
   • How to do it:
     • Right-click on your JavaEyes folder
     • Select CVS ~ Tag
     • In the space provided, type the tag that the instructor demands, spelled EXACTLY as you are told
       • Often we use Stage1, Stage2, etc., to tag the ends of Part 1, Part2, etc.
     • Look at the output and ask questions about it as necessary.