PHP pass array by reference

Question

1. What is a correct way to use array_splice in PHP? The function header clearly says:

   array_splice ( array &$input , int $offset... so it should accept reference as a first argument.

   However, a line

   array_push(&$this->contextsIds, $contextId);

   Triggers an error Deprecated: Call-time pass-by-reference has been deprecated in ... line 132

2. How do I return a reference to an array? I have:

   public function &getContextsIds() {
       return is_array($this->contextsIds) ? $this->contextsIds : array();    
   }
   

   but it says Notice: Only variable references should be returned by reference

Answer 1

1. The function is already declared to take a reference (array &$input); you don't need the & again when calling the function. Just call it like this:

   array_push($this->contextsIds, $contextId);
   

2. As the message says, you should only return actual variables by reference, not mere values. In your example, there are two such instances: the ? : operator evaluates to a value, and also array() by itself is just a value not bound to any variable. You should probably just return your class member regardless of whether it is empty or not:

   return $this->contextIds;
   

Answer 2

Why would you return a reference to an array, especially in the code you provided:

public function &getContextsIds() {
    return is_array($this->contextsIds) ? $this->contextsIds : array();    
}

When that function is would work, it could return a reference to an empty array, I could do with it what I want and change it as much as I'd like, but it wouldn't have any effect, because it was just an empty array without any further reference at all..