Why you should always use PHP interfaces

原文地址:http://www.davegardner.me.uk/blog/2010/11/21/why-you-should-always-use-php-interfaces/

在这里只列出文章里面的代码

// our interface

interface userInterface {

public function isMember();

}

// our concrete user class

class user implements userInterface {

private $paidUntil;

public function __construct($paidUntil) {

$this->paidUntil = $paidUntil;

}

public function isMember() {

return $paidUntil > time();

}

}

// our proxy

class userProxy implements userInterface {

private $dao;

private $user;

private $userId;

public function __construct($dao, $userId) {

$this->dao = $dao;

// set user to NULL to indicate we haven't loaded yet

$this->user = NULL;

}

public function isMember() {

if ($this->user === NULL) {

$this->lazyLoad();

}

return $this->user->isMember();

}

private function lazyLoad() {

$this->user = $this->dao->getById($this->userId);

}

}

class inviteList {

public function add(userInterface $user) {

if (!$user->isMember()) {

throw new youMustPayException('You must be a member to get an invite.');

}

// do something else

}

}