php - How to return special value when objected is casted to an array? -

there magic method __tostring, triggered if object used in string context or casted such, e.g.

<?php   class foo {     public function __tostring() {          return 'bar';    }  }   echo (string) new foo(); // return 'bar'; 

is there similar function triggered when object castend (array)?

no, there arrayaccess interface, allows use class array. looping functionality la foreach need interface iteratoraggregate or iterator. former easier use if have internal array using because need override 1 method (which provides instance of arrayiterator), latter allows more fine-grain control on iterating.

example:

class messages extends arrayaccess, iteratoraggregate {     private $messages = array();      public function offsetexists($offset) {         return array_key_exists($offset, $this->messages);     }      public function offsetget($offset) {         return $this->messages[$offset];     }      public function offsetset($offset, $value) {         $this->messages[$offset] = $value;     }      public function offsetunset($offset) {         unset($this->messages[$offset]);     }      public function getiterator() {         return new arrayiterator($this->messages);     } }  $messages = new messages(); $messages[0] = 'abc'; echo $messages[0]; // 'abc'  foreach($messages $message) { echo $message; } // 'abc'