Getting reference to array element where array is accessible as $obj->$propName

Suppose that we have this code (simplified example): ``` $propertyName = 'items'; $foo = new \stdClass; $foo->$propertyName = array(42); ``` At this point I 'd like to write an expression that evaluates to a reference to the value inside the array. Is it possible to do this? If so, how? An answer that will "do the job" but is not what I 'm looking for is this: ``` // Not acceptable: two statements $temp = &$foo->$propertyName; $temp = &$temp[0]; ``` But why write it as two statements? Well, because this will not work: ``` // Will not work: PHP's fantastic grammar strikes again // This is actually equivalent to $temp = &$foo->i $temp = &$foo->$propertyName[0]; ``` Of course `&$foo->items[0]` is another unacceptable solution because it fixes the property name. In case anyone is wondering about the strange requirements: I 'm doing this inside a loop where `$foo` itself is a reference to some node inside a graph. Any solution involving `$temp` would require an `unset($temp)` afterwards so that setting `$temp` on the next iteration does not completely mess up the graph; this `unset` requirement can be overlooked if you are not ultra careful around references, so I was wondering if there is a way to write this code such that there are less possibilities to introduce a bug.