deepfire / weld

A history rewriting tool for git.

What?

weld automates git history rewriting to ease pre-submission branch cleanup, mainly.

You could say it generalizes git-amend, by allowing different flavors of amending arbitrarily deep in history – and easier than what --interactive modes of git provide. But it’s actually more than just about amending.

So, without further ado – what it can do:

Modes of operation

weld A [B]

given any commits A and B, such that A is an ancestor of B, it “welds” B into A – by rewriting the current branch, so that:

1. A` == A + B
2. B disappears

B defaults to the tip of HEAD

weldit A, weldname A

edit commit message/author of any commit A in the current branch – by rewriting it, so that:

1. A` == A, but with a different commit message/author

Note, that weldname depends on author-id.sh being able to resolve committer nicknames into full names with emails.

weldrop A

drop any commit A from the current branch

weldui A

launch git-gui at any commit A, and make any changes “just work”:

• commit message
• commit splits
• changes added or dropped

weldmove A [B]

given any commits A and B, such that A is an ancestor of B, it B directly atop of A

B defaults to the tip of HEAD

Safety

No unwanted changes – is weld’s modus operandi.

This is achieved by:

Zero difference invariant

at the end of operation, as a mandatory step:

• weld verifies that git-diff between the origin and rewritten versions of the operated-on branch is zero
• if there is a difference, weld prints it out and asks what to do – since there might be a valid reason for the changes, so you get the options to:

  accept

  the branch that is changed with respect to its origin version

  abort

  the weld operation entirely

• this actually even includes weldrop, whose sole raison d’etre is changing the branch contents

Backup branches

..before doing anything

Clean state

..as a prerequisite for doing anything

Continuability

Whenever a cherry-pick or a rebase face a conflict, weld provides following options (through a command-line switch, otherwise interactively):

Abort

this is the default – abort the weld operation, restore peace of mind

Fix

does not abort, save the weld session, allowing you to:

fix and continue

this requires that you:

1. resolve the conflicts
2. stage conflict resolutions
3. weld --continue, or alternatively, to skip a commit that reduces to nothing – weld --continue --cont-skip

give up and still abort

when everything is just wrong, you can still always weld --abort

Continue immediately

you can resolve conflicts and stage resolutions while weld waits for your interactive input – unless there was a switch specified (--non-continuable or --continuable)