gistfile1.rb

class ScheduleGroup < ActiveRecord::Base
  include AbstractGroup
  has_and_belongs_to_many :schedules  
end


class Schedule < ActiveRecord::Base
  has_and_belongs_to_many :schedule_groups
end


module AbstractGroup
  before_destroy :removable?
  
  def removable?
    self.schedules.empty? # self.collection.empty?
  end
end

module AbstractGroup
  extend ActiveSupport::Concern

  included do
    class_inheritable_accessor :groupings
    self.groupings = []
    before_destroy :removable?
  end

  module ClassMethods
    def grouping(*associations)
      groupings.concat(*associations)
    end
  end

  def removable?
    self.class.groupings.all? { |grouping| send(grouping).empty? }
  end
end

g = ScheduleGroup.new(:name=>'test') TypeError: can't convert Symbol into Array from /Volumes/Devel/manager/app/models/abstract_group.rb:11:in `concat' from /Volumes/Devel/manager/app/models/abstract_group.rb:11:in`grouping' from /Volumes/Devel/manager/app/models/schedule_group.rb:3:in `<class:ScheduleGroup>' from /Volumes/Devel/manager/app/models/schedule_group.rb:1:in`<top (required)>'

…

On 2011-05-17, at 3:00 PM, samuelkadolph wrote: ``` ruby module AbstractGroup extend ActiveSupport::Concern included do class_inheritable_accessor :groupings self.groupings = [] before_destroy :removable? end module ClassMethods def grouping(*attributes) groupings.concat(*attributes) end end def removable? self.class.groupings.all? { |grouping| send(grouping).empty? } end end ``` ## Reply to this email directly or view it on GitHub: https://gist.github.com/977064

Sorry, make that groupings.concat(associations).