new

# File activerecord/lib/active_record/associations.rb, line 178
    def initialize(owner = nil, reflection = nil)
      if owner && reflection
        super("Cannot modify association '#{owner.class.name}##{reflection.name}' because the source reflection class '#{reflection.source_reflection.class_name}' is associated to '#{reflection.through_reflection.class_name}' via :#{reflection.source_reflection.macro}.")
      else
        super("Cannot modify association.")
      end
    end