Show changelog of what changed in mercurial repo + subrepos

gistfile1.rb

def subrepo_changed?(from = 'tip~1',to = 'tip')
  command = "hg status --rev #{from}:#{to} -m -a -r -d -S .hgsubstate"
  result = `#{command}`.include?("M .hgsubstate")
  return result
end

def subrepo_changes(from,to)
  command = "hg diff -S -r #{from}..#{to} .hgsubstate"
  result = `#{command}`

  changes =  result.split(/\n/).select{ |c| c.match(/^[-+][a-z0-9]/) }

  module_changes = Hash.new

  changes.each do |c|

    revision, name = c[1..-1].split(' ')

    module_changes[name] = Hash.new if module_changes[name].nil?

    module_changes[name][:from] = revision if c.start_with?('-')
    module_changes[name][:to] = revision if c.start_with?('+')
  end
  return module_changes
end

def show_log(from,to)
  command = "hg log -r#{from}:#{to} --style changelog"
  result = `#{command}`
  puts result
end

def show_changes(from,to)

  # Show log from - to revision
  show_log(from,to)

  # Now recurse subrepos
  if subrepo_changed?(from,to)
    changes = subrepo_changes(from,to)
    changes.each do |name, revisions|
      puts "---- #{name} -----------------------------------"
      Dir.chdir(name)
      show_changes(revisions[:from],revisions[:to])
      levels = name.match(File::Separator)
      if levels.nil?
        levels_back = 1
      else
        levels_back = levels.size + 1
      end

      levels_back.times { Dir.chdir('..') }
    end
  end

end

unless ARGV.size == 1
  puts "Usage: ruby whatchanged.rb [numberofrevisionsago]"
  exit
end

from = "tip~#{ARGV[0].to_i-1}"
to = 'tip'
show_changes(from,to)