BlaBla.cn

Returning References

Returning by-reference is useful when you want to use a function to find which variable a reference should be bound to. Do not use return-by-reference to increase performance, the engine is smart enough to optimize this on its own. Only return references when you have a valid technical reason to do it! To return references, use this syntax:

  <?php 
 class  foo  { 
    public  $value  =  42 ; 
 
    public function & getValue () { 
        return  $this -> value ; 
    } 
} 
 
 $obj  = new  foo ; 
 $myValue  = & $obj -> getValue ();  // $myValue is a reference to $obj->value, which is 42. 
 $obj -> value  =  2 ; 
echo  $myValue ;                 // prints the new value of $obj->value, i.e. 2. 
 ?>

In this example, the property of the object returned by the getValue function would be set, not the copy, as it would be without using reference syntax.

Note: Unlike parameter passing, here you have to use & in both places - to indicate that you return by-reference, not a copy as usual, and to indicate that reference binding, rather than usual assignment, should be done for $myValue.

Note: If you try to return a reference from a function with the syntax: return ($this->value); this will not work as you are attempting to return the result of an expression, and not a variable, by reference. You can only return variables by reference from a function - nothing else. E_NOTICE error is issued since PHP 4.4.0 and PHP 5.1.0 if the code tries to return a dynamic expression or a result of the new operator.

BlaBla.cn