Create a Gemfile (irc)

gemfile.rb

abort 'Aborting. Gemfile already exists.' if File.exists? 'Gemfile'

@requires = []

files = Dir['*.rb']
files.each do |file|
  open file do |file|
    file.each do |line|
      @requires << line.chomp if line.start_with? 'require '
    end
  end
end

@requires.map do |e|
  e.gsub!('require ', '').gsub!(/'|"/, '').gsub!('/', '-')
end

# TODO: Remove stdlib matches.

open 'Gemfile', 'w' do |file|
  file << "source 'https://rubygems.org'\n"
  @requires.each do |gem|
    file << "gem '#{gem}'\n"
  end
end
puts 'Gemfile created.'

A gem: https://github.com/shockone/gemper