aass Acts As State Setter (AASS)根据当前状态和指定条件设置对象的下一个状态

美国社会科学院Acts-As-State-Setter (AASS)是一个轻量级的状态机库。安装：将此行添加到应用程序的Gemfile中：gem 'aass', :git => \"git@github.com:kentan88/aass.git\", :branch => \"master\"。示例代码：

class Delivery < ActiveRecord::Base

  def set_status

    case status

    when 'unassigned'

      if can_assign?

        'assigned'

      elsif can_postponed?

        'postponed'

      else

        can_cancel?

        'cancelled'

      end

    end

  end

end