# File lib/rgen/instantiator/abstract_instantiator.rb, line 32
        def self.resolve_by_id(attribute, desc)
                id_attr = (desc.is_a?(Hash) && desc[:id])
                src_attr = (desc.is_a?(Hash) && desc[:src])
                raise StandardError.new("No id attribute given.") unless id_attr
                resolve(attribute) do
                        @env.find(id_attr => @current_object.send(src_attr)).first
                end
        end