Online PHP editor | output for 0942s

<?php // from http://stackoverflow.com/a/3764809/4251625 function refcount($var) { ob_start(); debug_zval_dump($var); $dump = ob_get_clean(); $matches = array(); preg_match('/refcount\(([0-9]+)/', $dump, $matches); $count = $matches[1]; //3 references are added, including when calling debug_zval_dump() return $count - 3; } class SomethingBuilder { protected $value; protected $listeners = []; protected function dispatchEvent($evt){ foreach($this->listeners as $listener) $listener($evt); } function addEventListener($listener){ $this->listeners[] = $listener; } function getValue(){ return $this->value; } function setValue($value){ $this->dispatchEvent('beforechange'); $this->value = $value; } function freeze(){ return new SomethingFinalBuilderWrapper($this); } } class SomethingFinalBuilderWrapper { protected $builder; function __construct(SomethingBuilder $builder){ $this->builder = $builder; $this->builder->addEventListener(function($evt){ if($evt !== 'beforechange') return; echo refcount($this->builder); // if(refcount($this->builder) > 1) $this->builder = clone $this->builder; echo "clone happened\n"; }); } function getValue(){ return $this->builder->getValue(); } } $x = new SomethingBuilder(); $x->setValue(10); echo $x->getValue() . "\n"; $y = $x->freeze(); $x->setValue(20); echo $y->getValue() . "\n"; echo $x->getValue() . "\n"; $y = $x->freeze(); $z = $x->freeze(); $x->setValue(20); echo $y->getValue() . "\n"; echo $x->getValue() . "\n";