gistfile1.rb

module ScopedTags
  
  module ActiveRecordAdditions
    
    def self.included(base)
      base.class_eval do
        def self.scoped_tags(contexts, options = nil)
          cattr_accessor :tag_contexts
          
          raise ScopedTagsError, 'context is required for scoped-tags setup' if contexts.blank?
          
          self.tag_contexts = [contexts].flatten
          
          has_many :taggings, :as => :taggable,       :class_name => 'Tagging', :dependent => :delete_all
          has_many :tags,     :through => :taggings,  :class_name => 'Tag',     :readonly => true
            
          self.tag_contexts.each do |context|
            has_many context, :through => :taggings, :class_name => 'Tag',
                              :source  => :tag,
                              :conditions => ["context = ?", context.to_s.downcase]
            
            c = context.to_s.singularize
            define_method("#{c}_list")   { get_tag_list(context.to_s.downcase) }
            define_method("#{c}_list=")  { |new_list| set_tag_list(context.to_s.downcase, new_list) }
            self.class.instance_eval do
              define_method("tagged_with_#{context}") { |context_names|  }
            end
          end          
          
          self.send :include, InstanceMethods
        end
      end
    end
  end
end