List git branches with a numerical index, then check a branch out by index

git-list.rb

#!/usr/bin/env ruby

# To setup - copy this to a file named git-list in a directory on your path and 
# chmod +x.
#
# To use - Type git list, and select the branch you'd like to check out.

@branches = Array.new

class String
  def white
    "\033[37m#{self}\033[0m"
  end
  def bg_green
    "\033[42m#{self}\033[0m"
  end
end

def list_branches
  @branches = `git branch -l`.split("\n").map do |branch|
    branch.strip
  end
  @branches.each_with_index do |branch, index|
    if branch.include? "*"
      puts "#{index + 1}.\t" + "#{branch.split("*")[1].strip}".bg_green.white
    else
      puts "#{index + 1}.\t#{branch}" 
    end
  end
end

def checkout_branch(branch_index)
  `git checkout #{@branches[branch_index - 1]}`
end

list_branches
print "Checkout branch: "
branch_index = gets
if (branch_index =~ /^\d+$/)
  puts "Checking out branch #{@branches[branch_index.to_i - 1]}..."
  checkout_branch(branch_index.to_i)
end