gistfile1.rb

class Task
  attr_accessor :name, :parent

  def initialize(name)
    @name = name 
    @parent = nil
  end

  def get_time_required
    0.0
  end
end


class CompositeTask < Task
  def initialize(name)
    super(name)
    @sub_tasks = []
  end

  def add_sub_task(task)
    @sub_tasks << task 
    task.parent = self
  end

  def remove_sub_task(task) 
    @sub_tasks.delete(task) 
    task.parent = nil
  end

  def get_time_required
    time=0.0
    @sub_tasks.each {|task| time += task.get_time_required}
    time
  end
end