PHP 객체 지향 프로그래밍의 템플릿 패턴 살펴보기

<?php
abstract class ShoppingCartTemplate {
    // 模板方法，定义购物车算法的框架
    public final function processCart() {
        $this->addItems();
        $this->calculateTotal();
        $this->showCart();
    }
    
    // 添加商品的具体实现由子类来完成
    protected abstract function addItems();
    
    // 计算总价的具体实现由子类来完成
    protected abstract function calculateTotal();
    
    //展示购物车的具体实现由子类来完成
    protected abstract function showCart();
}

class ShoppingCart1 extends ShoppingCartTemplate {
    protected function addItems() {
        echo "添加商品到购物车1中。<br/>";
    }
    
    protected function calculateTotal() {
        echo "计算购物车1的总价。<br/>";
    }
    
    protected function showCart() {
        echo "展示购物车1中的商品。<br/>";
    }
}

class ShoppingCart2 extends ShoppingCartTemplate {
    protected function addItems() {
        echo "添加商品到购物车2中。<br/>";
    }
    
    protected function calculateTotal() {
        echo "计算购物车2的总价。<br/>";
    }
    
    protected function showCart() {
        echo "展示购物车2中的商品。<br/>";
    }
}

// 调用购物车1
$cart1 = new ShoppingCart1();
$cart1->processCart();

echo "<br/>";

// 调用购物车2
$cart2 = new ShoppingCart2();
$cart2->processCart();
?>