lab 34 Rebasing

Goals

Ok, we are back in time before the first merge and we want to get the changes in master into our greet branch.

This time we will use the rebase command instead of the merge command to bring in the changes from the master branch.

Execute:

git checkout greet
git rebase master
git hist

Output:

$ go greet
Switched to branch 'greet'
$
$ git rebase master
First, rewinding head to replay your work on top of it...
Applying: added Greeter class
Applying: hello uses Greeter
Applying: updated Rakefile
$
$ git hist
* b818028 2014-10-25 | Updated Rakefile (HEAD, greet) [Jim Weirich]
* b790264 2014-10-25 | Hello uses Greeter [Jim Weirich]
* 0a576ce 2014-10-25 | Added greeter class [Jim Weirich]
* 6fd9eff 2014-10-25 | Added README (master) [Jim Weirich]
* 14ba469 2014-10-25 | Added a Rakefile. [Jim Weirich]
* 4b249b3 2014-10-25 | Moved hello.rb to lib [Jim Weirich]
* bfd1408 2014-10-25 | Add an author/email comment [Jim Weirich]
* a1189df 2014-10-25 | Added a comment (tag: v1) [Jim Weirich]
* 6083cb8 2014-10-25 | Added a default value (tag: v1-beta) [Jim Weirich]
* b24f3ff 2014-10-25 | Using ARGV [Jim Weirich]
* cf466b4 2014-10-25 | First Commit [Jim Weirich]

Merge VS Rebase 01

The final result of the rebase is very similar to the merge. The greet branch now contains all of its changes, as well as all the changes from the master branch. However, the commit tree is quite different. The commit tree for the greet branch has been rewritten so that the master branch is a part of the commit history. This leaves the chain of commits linear and much easier to read.

When to Rebase, When to Merge? 02

Don’t use rebase …

  1. If the branch is public and shared with others. Rewriting publicly shared branches will tend to screw up other members of the team.
  2. When the exact history of the commit branch is important (since rebase rewrites the commit history).

Given the above guidelines, I tend to use rebase for short-lived, local branches and merge for branches in the public repository.

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