php设计模式小结

    // other vars..

    private function __construct() {
        // do construct..
    }

    private function __clone() {}

    public static function getInstance() {
        if (!(self::$instance instanceof self)) {
            self::$instance = new self();
        }
        return self::$instance;
    }

    // other functions..
}

$a = SingetonBasic::getInstance();
$b = SingetonBasic::getInstance();
var_dump($a === $b);

    }
}

// 定义矩形类
class Rectangle implements IShape {
    private $width, $height;

    public function __construct($width, $height) {
        $this->width = $width;
        $this->height = $height;
    }

    public function getCircum() {
        return 2 ($this->width + $this->height);
    }

    public function getArea() {
        return $this->width $this->height;
    }
}

// 定义圆类
class Circle implements IShape {
    private $radii;

    public function __construct($radii) {
        $this->radii = $radii;
    }

    public function getCircum() {
        return 2 M_PI $this->radii;
    }

    public function getArea() {
        return M_PI pow($this->radii, 2);
    }
}

// 根据传入的参数个数不同来创建不同的形状。
class FactoryShape {
    public static function create() {
        switch (func_num_args()) {
            case 1:
                return new Circle(func_get_arg(0));
                break;
            case 2:
                return new Rectangle(func_get_arg(0), func_get_arg(1));
                break;

        }
    }
}

// 矩形对象
$c = FactoryShape::create(4, 2);
var_dump($c->getArea());
// 圆对象
$o = FactoryShape::create(2);
var_dump($o->getArea());

// 可被观察接口
interface IObservable {
    function addObserver($observer);
    function removeObserver($observer_name);
}

// 观察者类
abstract class Observer implements IObserver {
    protected $name;

    public function getName() {
        return $this->name;
    }
}

// 可被观察类
class Observable implements IObservable {
    protected $observers = array();

    public function addObserver($observer) {
        if (!($observer instanceof IObserver)) {
            return;
        }
        $this->observers[] = $observer;
    }

    public function removeObserver($observer_name) {
        foreach ($this->observers as $index => $observer) {
            if ($observer->getName() === $observer_name) {
                array_splice($this->observers, $index, 1);
                return;
            }
        }
    }
}

// 模拟一个可以被观察的类RadioStation
class RadioStation extends Observable {

    public function addListener($listener) {
        foreach ($this->observers as $observer) {
            $observer->onListen($this, $listener);
        }
    }
}

// 模拟一个观察者类
class RadioStationLogger extends Observer {
    protected $name = 'logger';

    public function onListen($sender, $args) {
        echo $args, ' join the radiostation.<br/>';
    }
}

// 模拟一个观察者类
class OtherObserver extends Observer {
    protected $name = 'other';
    public function onListen($sender, $args) {
        echo 'other observer..<br/>';
    }
}

$rs = new RadioStation();

// 注入观察者
$rs->addObserver(new RadioStationLogger());
$rs->addObserver(new OtherObserver());

// 移除观察者
$rs->removeObserver('other');

// 可以看到观察到的信息
$rs->addListener('tv');