Estoy tratando de tener un paquete de ámbitos con nombres muy genéricos para los modelos ActiveRecord como este:

module Scopes
  def self.included(base)
    base.class_eval do
      named_scope :not_older_than, lambda {|interval|
        {:conditions => ["#{table_name}.created_at >= ?", interval.ago]
      }
    end
  end
end
ActiveRecord::Base.send(:include, Scopes)

class User < ActiveRecord::Base
end

Si el ámbito con nombre debe ser general, debemos especificar * nombre_tabla * para evitar problemas de nomenclatura si se trata de uniones que provienen de otro ámbito con nombre encadenado.

El problema es que no podemos obtener table_name porque se llama en ActiveRecord :: Base en lugar de en User.

User.not_older_than(1.week)

NoMethodError: undefined method `abstract_class?' for Object:Class
from /var/lib/gems/1.8/gems/activerecord-2.3.5/lib/active_record/base.rb:2207:in `class_of_active_record_descendant'
from /var/lib/gems/1.8/gems/activerecord-2.3.5/lib/active_record/base.rb:1462:in `base_class'
from /var/lib/gems/1.8/gems/activerecord-2.3.5/lib/active_record/base.rb:1138:in `reset_table_name'
from /var/lib/gems/1.8/gems/activerecord-2.3.5/lib/active_record/base.rb:1134:in `table_name'
from /home/bogdan/makabu/railsware/startwire/repository/lib/core_ext/active_record/base.rb:15:in `included'
from /var/lib/gems/1.8/gems/activerecord-2.3.5/lib/active_record/named_scope.rb:92:in `call'
from /var/lib/gems/1.8/gems/activerecord-2.3.5/lib/active_record/named_scope.rb:92:in `named_scope'
from /var/lib/gems/1.8/gems/activerecord-2.3.5/lib/active_record/named_scope.rb:97:in `call'
from /var/lib/gems/1.8/gems/activerecord-2.3.5/lib/active_record/named_scope.rb:97:in `not_older_than'

¿Cómo puedo obtener nombre_tabla real en el módulo de ámbitos?