git subtree

git subtree

Git subtrees are like submodules, but better and easier for everyone involved. They allow you to import code from a different repository but instead of adding a reference to your repository, they add the actual code and commit saying where the code came from.

The great thing about subtrees is if you do not care about merging or splitting them, they do not affect you. You can treat the whole repository as you would normally. If the above describes you, you can stop reading now.

Installing

If you use OSX and homebrew, then brew install git will install the subtree command along with git.

Otherwise it is a single script you can download:

1. Download https://raw.github.com/git/git/master/contrib/subtree/git-subtree.sh
2. Make executable: chmod a+x git-subtree.sh
3. Rename to git-subtree: mv git-subtree.sh git-subtree
4. Move to a directory on your PATH

Using

Each section below has a description and example for each command, and a list of the subtrees in each of the montagejs repositories with the command that you can copy and paste. See the Adding section for an example of what a subtree looks like.

Merging/pulling

This will merge updates from the other repository while keeping any changes made to the subtree locally (for example deleted files).

git subtree pull --squash --prefix=$dir$ [email protected]:$repo$.git $commitOrTag$ -m "Update $name$ to $version$"

Mr ↣ Montage

git subtree pull --squash --prefix=packages/mr [email protected]:montagejs/mr.git $version -m "Update Mr to $version$"

Q ↣ Mr

git subtree pull --squash --prefix=packages/q [email protected]:kriskowal/q.git $version -m "Update Q to $version"

Popcorn ↣ montagejs.org

git subtree pull --squash --prefix=source/apps/popcorn [email protected]:montagejs/popcorn.git master -m "Update Popcorn to master"

Kitchen sink ↣ montagejs.org

git subtree pull --squash --prefix=source/docs/kitchen-sink [email protected]:montagejs/kitchen-sink.git master -m "Update Kitchen sink to master"

Splitting

Splitting allows you take take changes to the subtree from your repository and commit them to the other one.

TODO: Write after splitting for the first time

Adding

This will add all the files in repo at commit under dir, and will create 2 commits

git subtree add --squash --prefix=$dir$ [email protected]:$repo$.git $commitOrTag$ -m "Add $name$ $version$ as a subtree"

commit 25303c2f71a7437f6cb4d8f2e277a2c0aca6040c
Author: Stuart Knightley <[email protected]>
Date:   Tue Jan 8 16:49:33 2013 +0000

    Squashed 'packages/mr/' content from commit fb221b7
    
    git-subtree-dir: packages/mr
    git-subtree-split: fb221b7322e581ab63aa5a8bdbf8ae5579c6b06c

commit f3cf33549b20e42da24bd55c211af8307092341a
Merge: 3e6a9e2 25303c2
Author: Stuart Knightley <[email protected]>
Date:   Tue Jan 8 16:49:33 2013 +0000

    Add Mr v0.12.0 as a subtree