Encapsulate git

Here is a solution to maintain divergent branches in git. Because it is easy to merge by mistake. I give a script that encapsulate git in order to forbid some merge and warn you some merge should be dangerous.

how to protect against your own dumb

I work on a project in which some of my git branches should remain divergent. And divergences should grow.

I also use some branch to contain what is common between projects.

Say I have some branches:

master: common to all branches dev: branch devoted to unstable development client: branch with features for all client but not general enough for master clientA: project adapted for client A clientB: project adapted for client B

Here how I want to work:

Dynamic branching

And more precisely the branch hierarchy:

Branch hierarchy

An arrow from A to B means, you can merge A in B. If there is no arrow from A to B that means it is forbidden to merge A in B. Here is the corresponding rubycode:

$architecture={ :master => [ :dev, :client ], :dev => [ :master ], :client => [ :clientA, :clientB ] }

Having a :master => [ :dev, :client ] means you can merge master branch into dev and client.

If by mistake I make a git checkout master && git merge clientA, I made a mistake. This is why I made a script which encapsulate the git behaviour to dodge this kind of mistake.

But this script do far more than that. It also merge from top to down. The action allmerges will do:

git co dev && git merge master git co client && git merge master git co clientA && git merge client git co clientB && git merge client

That means, I can update all branches. The algorithm will not make loop even if there is a cycle in the branch hierarchy.

Here it is:

#!/usr/bin/env ruby # encoding: utf-8

architecture

master <-> dev

master -> client

clien -> clientA | clientB

merge using two of these branches should be

restricted to these rules

merge to one of these branch and an unknown one should

raise a warning, and may the option to add this new branch

to the hierarchy

$architecture={ :master => [ :dev, :client ], :dev => [ :master ], :client => [ :clientA, :clientB ] }

def get_current_branch() (git branch --no-color | awk '$1 == "*" {print $2}').chop.intern end

if ARGV.length == 0 puts %{usage: $0:t [git_command or local_command]

local commands: allmerges: merge from top to down} exit 0 end

require ‘set’ knownbranches = Set. newarchitecture.each do |k,v| $known_branches.add(k) v.each { |b| $known_branches.add(b) } end

def rec_merge(branch) if architecture[branch]. nil? returnendarchitecture[branch].each do |b| if flag. haskey? (b. tos + branch. tos)nextendflagname = branch. tos + b. tosifflag.has_key?(flagname) next end if system %{eng checkout #{b}} if get_current_branch != b puts “Can’t checkout to #{b}” exit 2 end if system %{eng merge #{branch}} $flag[flagname]=true rec_merge(b) else exit 1 end else exit 1 end end end

def do_all_merges puts ‘Will merge from father to sons’ current_branch=get_current_branch $flag={} rec_merge(:master) system %{git co #{current_branch}} end

def do_merge current_branch=get_current_branch src_branch=ARGV[1].intern puts %{do_merge: #{src_branch} => #{current_branch}} if knownbranches. include? (currentbranch)ifknown_branches.include?(src_branch) if architecture. haskey? (srcbranch)andarchitecture[src_branch].include?(current_branch) system %{git merge #{src_branch}} else puts %{Forbidden merge: #{src_branch} => #{current_branch}} end else puts %{Warning! #{src_branch} not mentionned in rb configuration} sleep 2 system %{git merge #{src_branch}} puts %{Warning! #{src_branch} not mentionned in rb configuration} end end end

case ARGV[0] when ‘allmerges’ then do_all_merges when ‘merge’ then do_merge else system %{git #{ARGV.join(‘’)}} end

All you need to do to make it work is simply to copy eng in a directory contained in your PATH.

Of course try to use as few as possible cherry-pick and rebase. This script was intended to work with workflow using pull and merge.

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Published on 2010-03-23
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Yann Esposito©
Done with Vim & nanoc Hakyll