Online PHP editor | output for FuX4X

<?php interface Counter { /** @return self */ public function count(); /** @return int */ public function getCount(); } class EchoingCounter implements Counter { private $counter; public function __construct(Counter $counter) { $this->counter = $counter; } public function count() { echo __METHOD__ . "\n"; $this->counter->count(); return $this; } public function getCount() { echo __METHOD__ . "\n"; return $this->counter->getCount(); } } class ImmutableCounter implements Counter { private $count; public function __construct($count = 0) { $this->count = (int) $count; } public function count() { return new ImmutableCounter($this->count + 1); } public function getCount() { return $this->count; } } $counter = new EchoingCounter(new ImmutableCounter()); $counter = $counter->count()->count()->count()->count(); echo $counter->getCount();