associations_has_many.rb

 module Associations
   ....
     
   def has_many(association_id, options = {}, &extension)
     reflection = create_has_many_reflection(association_id, options, &extension)
     configure_dependency_for_has_many(reflection)
     add_association_callbacks(reflection.name, reflection.options)
     if options[:through]
       collection_accessor_methods(reflection, HasManyThroughAssociation)
     else
       collection_accessor_methods(reflection, HasManyAssociation)
     end
   end
   
   ....
 end