We covered a lot of ground in this chapter. We discussed the concepts of tags and branches and demonstrated how Subversion implements these concepts by copying directories with the svn copy command. We showed how to use svn merge to copy changes from one branch to another or roll back bad changes. We went over the use of svn switch to create mixed-location working copies. And we talked about how one might manage the organization and lifetimes of branches in a repository.

Remember the Subversion mantra: branches and tags are cheap. So don't be afraid to use them when needed!

As a helpful reminder of all the operations we discussed, here is handy reference table you can consult as you begin to make use of branches.

Table 4.1. Branching and merging commands

Action Command
Create a branch or tag svn copy URL1 URL2
Switch a working copy to a branch or tag svn switch URL
Synchronize a branch with trunk svn merge trunkURL; svn commit
See merge history or eligible changesets svn mergeinfo SOURCE TARGET
Merge a branch back into trunk svn merge --reintegrate branchURL; svn commit
Merge one specific change svn merge -c REV URL; svn commit
Merge a range of changes svn merge -r REV1:REV2 URL; svn commit
Block a change from automatic merging svn merge -c REV --record-only URL; svn commit
Preview a merge svn merge URL --dry-run
Abandon merge results svn revert -R .
Resurrect something from history svn copy URL@REV localPATH
Undo a committed change svn merge -c -REV URL; svn commit
Examine merge-sensitive history svn log -g; svn blame -g
Create a tag from a working copy svn copy . tagURL
Rearrange a branch or tag svn move URL1 URL2
Remove a branch or tag svn delete URL