private function _parseConstructorArgument(__ConfigurationSection $property, __InstanceDefinition &$instance_definition) { if ($property->hasAttribute('index')) { $argument_index = $property->getAttribute('index'); } else { $argument_index = null; } $argument_value = $this->_parsePropertyValue($property, 'constructor argument', $instance_definition->getId()); $instance_definition->addConstructorArgument($argument_value, $argument_index); }