PHP中abstract种中有abstract方法是否最先执行abstract方法，然后才执行其他方法

<br />
abstract class Node {<br />
		private $debugMessages;<br />
		<br />
		public function __construct() {<br />
			$this->debugMessages = array();<br />
			$this->debug(__CLASS__.' constructor called.');<br />
		}<br />
		<br />
		public function __destruct() {<br />
			$this->debug(__CLASS__.' destructor called.');<br />
			$this->dumpDebug();<br />
		}<br />
		<br />
		protected function debug($msg) {<br />
			$this->debugMessages[] = $msg;<br />
		}<br />
		<br />
		private function dumpDebug() {<br />
			echo implode('<br />', $this->debugMessages);<br />
		}<br />
		<br />
		public abstract function getView();<br />
	}<br />
	<br />
	<br />
	class ForumTopic extends Node {<br />
		private $debugMessages;<br />
		<br />
		public function __construct() {<br />
			parent::__construct();<br />
			$this->debug(__CLASS__.' constructor called.');<br />
		}<br />
		<br />
		public function __destruct() {<br />
			$this->debug(__CLASS__.' destructor called.');<br />
			parent::__destruct();<br />
		}<br />
		<br />
		public function getView() {<br />
			return 'This is a view into '.__CLASS__.'<br />';<br />
		}<br />
	}<br />
	<br />
	$forum = new ForumTopic();<br />
	echo $forum->getView();<br />