Today I Learned Git

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Use a file from another branch #

Sometimes you just need one file from another branch. Sure you could git cherry-pick but then you're dealing with commits. That sort of thing gets sticky fast; don't go there.

The best way is to use your old pal git checkout. Just make sure you're on the branch you want to bring the file into and then checkout the file from its source branch. Here's the syntax.

git checkout my-awesome-source-branch the/path/to/yourfile.rad

That's it – enjoy.

Split Up a Commit, Rewrite History #

When working on a branch with multiple commits, you can "go back in time" and revise previous commits any way you please.

git rebase -i origin/master

This command will prompt you inside of your $VISUAL with a series of commit SHAs and commit titles

# ...
pick ed1ff41 Move templates
pick 274ac0e Move components & views
# ...

To split up 274ac0e, replace pick with edit and save the buffer.

# ...
pick ed1ff41 Move templates
edit 274ac0e Move components & views
# ...

You are now detached from the HEAD of your branch and "back in time". To split up the current commit (274ac0e):

git reset HEAD~

This will unstage all files within the commit. Next, split up the commit any way you'd like.

git add app/views
git commit -m "Move views"
git add app/components
git commit -m "Move components"

When you're finished, continue the rebase.

git rebase --continue

If you introduced merge conflicts down the line, you'll have to resolve them. If all went well, your branch's history will be re-written.

git log origin/master..

# ...
ed1ff41 Move templates
7b84a01 Move views
274ac0e Move components
# ...

Keep in mind that you might have to force push your branch to origin, depending on whether or not your revised commits have been pushed.

git push origin my-branch-name --force

Two ways of squashing commits #

It is handy to squash down your commits before merging your PR with my-new-cool-feature. You can either squash them down by doing an interactive rebase like so:

git checkout my-new-cool-feature
git rebase -i master

This will open up your $EDITOR of choice and you are free to pick and choose which commits to squash together.

This might be tedious if you have a big number of commits to squash together. Very tedious. TIL that you can use git merge to squash your commits, all in one go.

git checkout master
git merge --squash my-cool-new-feature

This will leave all of your changes staged on master, ready to be committed as one.

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