シンプルなデリゲートの実装

C#ライクなデリゲートの実装

<?php

class Delegate
{
	/** @var callable[] */
	protected $callbacks = [];

	/**
	 * Add callback function
	 * @param callable $callback
	 * @return $this
	 */
	public function add(callable $callback)
	{
		$this->callbacks[] = $callback;
		return $this;
	}

	/**
	 * Remove callback function
	 * @param callable $callback
	 * @return $this
	 */
	public function remove(callable $callback)
	{
		foreach ( $this->callbacks as $key => $_callback )
		{
			if ( $callback == $_callback )
			{
				unset($this->callbacks[$key]);
				return $this;
			}
		}
		return $this;
	}

	/**
	 * Invoke callback functions
	 * @return mixed
	 */
	public function __invoke()
	{
		$result = null;

		foreach ( $this->callbacks as $callback )
		{
			$result = call_user_func_array($callback, func_get_args());
		}

		return $result;
	}
}

$callback = function($name) {
	echo "Hello $name", PHP_EOL;
};

$delegate = new Delegate();
$delegate
	->add($callback)
	->add($callback)
	->remove($callback);

$delegate("World");