Rails::Generator::Commands::Base.class_eval do
  def file_contains?(relative_destination, line)
    File.read(destination_path(relative_destination)).include?(line)
  end
end
 
Rails::Generator::Commands::Create.class_eval do
  def insert_into(file, line)
    logger.insert "#{line} into #{file}"
    unless options[:pretend] || file_contains?(file, line)
      gsub_file file, /^(class|module) .+$/ do |match|
        "#{match}\n #{line}"
      end
    end
  end
end
 
Rails::Generator::Commands::Destroy.class_eval do
  def insert_into(file, line)
    logger.remove "#{line} from #{file}"
    unless options[:pretend]
      gsub_file file, "\n #{line}", ''
    end
  end
end
 
Rails::Generator::Commands::List.class_eval do
  def insert_into(file, line)
    logger.insert "#{line} into #{file}"
  end
end