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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
* ff7c118 2019-11-01 | Updated Rakefile (HEAD -> greet) [Jim Weirich]
* 2a262be 2019-11-01 | Hello uses Greeter [Jim Weirich]
* 413c34f 2019-11-01 | Added greeter class [Jim Weirich]
* 099ccd0 2019-11-01 | Added README (master) [Jim Weirich]
* ed35144 2019-11-01 | Added a Rakefile. [Jim Weirich]
* 4421854 2019-11-01 | Moved hello.rb to lib [Jim Weirich]
* 185fc95 2019-11-01 | Add an author/email comment [Jim Weirich]
* 4d578d4 2019-11-01 | Added a comment (tag: v1) [Jim Weirich]
* dc1d42f 2019-11-01 | Added a default value (tag: v1-beta) [Jim Weirich]
* 9a1c494 2019-11-01 | Using ARGV [Jim Weirich]
* 063b40e 2019-11-01 | First Commit [Jim Weirich]

Merge VS Rebase

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?

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.