class Gem::RDoc

def self.generation_hook installer, specs
  start = Time.now
  types = installer.document
  generate_rdoc = types.include? 'rdoc'
  generate_ri   = types.include? 'ri'
  specs.each do |spec|
    new(spec, generate_rdoc, generate_ri).generate
  end
  return unless generate_rdoc or generate_ri
  duration = (Time.now - start).to_i
  names    = specs.map(&:name).join ', '
  say "Done installing documentation for #{names} after #{duration} seconds"
end