class Rails::Generators::MailerGenerator

def create_mailer_file
  template "mailer.rb", File.join("app/mailers", class_path, "#{file_name}_mailer.rb")
  in_root do
    if behavior == :invoke && !File.exist?(application_mailer_file_name)
      template "application_mailer.rb", application_mailer_file_name
    end
  end
end