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.
?>
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.