PHP オブジェクト指向プログラミングにおける戦略パターンの分析

abstract class PriceStrategy {
    abstract public function calculatePrice($price);
}

class RegularStrategy extends PriceStrategy {
    public function calculatePrice($price) {
        return $price;
    }
}

class VipStrategy extends PriceStrategy {
    public function calculatePrice($price) {
        return $price * 0.9;
    }
}

class SvipStrategy extends PriceStrategy {
    public function calculatePrice($price) {
        return $price * 0.8;
    }
}

class Order {
    private $priceStrategy;

    public function setPriceStrategy(PriceStrategy $strategy) {
        $this->priceStrategy = $strategy;
    }

    public function calculateTotalPrice($price) {
        return $this->priceStrategy->calculatePrice($price);
    }
}

$order = new Order();

$regularStrategy = new RegularStrategy();
$order->setPriceStrategy($regularStrategy);
$regularPrice = $order->calculateTotalPrice(100); // 普通用户不打折，计算结果为100

$vipStrategy = new VipStrategy();
$order->setPriceStrategy($vipStrategy);
$vipPrice = $order->calculateTotalPrice(100); // VIP用户9折优惠，计算结果为90

$svipStrategy = new SvipStrategy();
$order->setPriceStrategy($svipStrategy);
$svipPrice = $order->calculateTotalPrice(100); // SVIP用户8折优惠，计算结果为80