Class to retrieve values lazily from a callback

Lazy.php

<?php
//+ Jonas Raoni Soares Silva
//@ http://raoni.org

class Lazy {
	private $_cache;
	private $_handler;

	public function __construct(callable $handler)
	{
		$this->_handler = $handler;
	}

	public function __invoke()
	{
		$key = $this->_hash(func_get_args());
		return array_key_exists($key, $this->_cache ?? []) ? $this->_cache[$key] : ($this->_cache[$key] = ($this->_handler)(...func_get_args()));
	}

	public function reset(): void
	{
		$this->_cache = null;
	}

	public function isCached(): bool
	{
		return array_key_exists($this->_hash(func_get_args()), $this->_cache ?? []);
	}

	private function _hash($data): string
	{
		return serialize($data);
	}
}

$lazy = new Lazy(function ($data){
	echo "Lazy run $data\n";
});
$lazy('A');
$lazy('A');
$lazy('A');
$lazy('B');