一个公司网站的价格,紫色风格网站,网站举报查询进度,wordpress阅读数 显示kC++访问者模式
一、模式痛点：当if-else成为维护噩梦
开发动物园管理系统，最初的需求很简单：
class Animal {};
class Cat : public Animal {};
class Dog : public Animal {};// 处理动物叫声
void makeSound(Animal* a) {if (auto c = dynamic_castCat*(a)) {st…
C++访问者模式
一、模式痛点：当if-else成为维护噩梦
开发动物园管理系统，最初的需求很简单：
class Animal {};
class Cat : public Animal {};
class Dog : public Animal {};// 处理动物叫声
void makeSound(Animal* a) {if (auto c = dynamic_castCat*(a)) {std::cout "Meow!\n";} else if (auto d = dynamic_castDog*(a)) {std::cout "Woof!\n";}
}当新增喂养功能时，代码迅速腐化：
void feedAnimal(Animal* a) {if (auto c = dynamic_castCat*(a)) {std::cout "Give fish\n";} else if (auto d = dynamic_castDog*(a)) {std::cout "Give bone\n";}
}系统痛点：
每新增功能就要修改所有类型判断逻辑类型检查与业务逻辑高度耦合违反开放封闭原则（OCP）二、模式实现：双分派的艺术
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