dependency injection

gistfile1.rb

class Trial
  def check_activity
    if activity > 100
      send_mail(Mailer)
    end
  end

  def send_mail(mail)
    mail.new(id, name, date, total_activity)
  end
end

class Mailer
  def initialize(id, name, date, total_activity)
    # blabla
  end
end