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Bez Hermoso, Software Engineer @ Square

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Concise value re-use pattern using PHP 7.x's null coalescing operator

22 Jan 2020

Since PHP 7.0, the addition of the null coalescing operator ?? has made writing certain boilerplate patterns obsolete, like the common pattern of using isset(...) to avoid a myriad of errors when addressing deeply-nested array elements that don’t exist.

Another pattern that is ripe for replacement is for value re-use, like those usually found in singletons, in-memory caches, memoizations:

<?php

class Singleton
{
		private static $instance;

		private function __construct() { ... };

		public static function getInstance(): Singleton
		{
				return self::$instance = self::$instance ?? new static();
		}
}

<?php

class Fibonacci
{
		private $cache = [];

		public function find($n): int
		{
				return $this->cache[$n] =
					$this->cache[$n] ?? self::find($n) + self::find($n - 2);
		}
}

See PHP 7.0 - New Features: null coalescing operator