Question

I have a magic __set($name, $value) method. Within __set(), Is there a way I can detect if the array append short-hand was used so it doesn’t blow away pre-existing values?

class Foo extends ArrayObject {

  protected $bar = array();

  public function __set($name, $value) {
    $this->bar = $value; // I want to handle both replace AND append
  }
}

$foobar = new Foo;
$foobar->bar = array('first element');
$foobar->bar[] = 'new element';

How can I handle this situation?

Answer 1

You can use __get to achieve what you want.

class Foo {

  protected $bar = array();

  public function &__get($name) {
    return $this->$name;
  }

  public function __set($name, $value) {
    $this->$name = $value;
  }
}

$foobar = new Foo;
$foobar->bar = array('first element');
$foobar->bar[] = 'new element';
print_r($foobar->bar);

This is because the []= operation first reads the property, then appends the element.

Note that __get must return ‘by reference’ for this to work (at least in PHP 5.4); if it does not return by reference you get a notice about indirect modification.

NOTE: also, at this point, you’d probably be as well making it public as the effect is basically the same.