修饰器模式

// 装饰器接口
interface Decorator
{
    function beforeDecorator();
    function afterDecorator();
}

// 改变颜色的装饰器
class ColorDecorator implements Decorator
{
    function __construct( $color="red" )
    {
        $this->color = $color;
    }
    function beforeDecorator()
    {
        echo "<div style='color:{$this->color}'>";
    }
    function afterDecorator()
    {
        echo '<div>';
    }
}

// 改变字体大小的装饰器
class SizeDecorator implements Decorator
{
    function __construct( $size="12px" )
    {
        $this->size = $size;
    }
    // 代码之前插入
    function beforeDecorator()
    {
        echo "<div style='font-size:{$this->size}'>";
    }
    // 代码之后插入
    function afterDecorator()
    {
        echo '<div>';
    }
}

class Test
{
    protected $decorators = array();

    function index()
    {
        $this->befor();
            echo '这是一个装饰器模式的小栗子';
        $this->after();
    }

    function befor()
    {
        foreach ($this->decorators as $key => $decorator) {
            $decorator->beforeDecorator();
        }
    }

    function after()
    {
        $this->decorators = array_reverse($this->decorators);
        foreach ($this->decorators as $key => $decorator) {
            $decorator->afterDecorator();
        }
    }

    function addDecorator( $decorator )
    {
        $this->decorators[] = $decorator;
    }
}

$test = new Test();
$test->addDecorator( new ColorDecorator('blue') );
$test->addDecorator( new SizeDecorator('24px') );
$test->index();