装饰模式(大话设计模式)C/C++版本

大家好，欢迎来到IT知识分享网。

装饰模式

需求分析：

1. 选择服饰 => 服饰类 2. 输出结果 对象是人 => 人类 

将Person类中一大堆服饰功能抽象出服饰类，然后通过Person类聚合服饰属性，通过Set行为来设置服饰属性，最后达到灵活打扮的效果

使用场景

之前：旧类新增功能，向旧类添加新的属性和新的行为，增加了类的复杂度，破坏了开闭原则； 现在：装饰功能作为一个单独类存在，就可以在运行时灵活的增加到旧类中。 

C++

#include <iostream> using namespace std; // ConcreteComponent即Component class Person { 
    protected: string name; public: Person(){ 
   }; Person(string name) : name(name){ 
   }; virtual void show() { 
    cout << "装扮的" << name << endl; } }; // Decorator类（装饰类），继承了Persson类，并且弱拥有Person类 class Finery : public Person { 
    protected: Person *component; public: Finery() : component(nullptr) { 
   } void Decorate(Person *component) { 
    this->component = component; } virtual void show() { 
    if (component) component->show(); } }; // ConcreteDecorator类 class TShirts : public Finery { 
    public: virtual ~TShirts() { 
   } virtual void show() { 
    cout << "Tshirt" << endl; Finery::show(); } }; // ConcreteDecorator类 class Jeans : public Finery { 
    public: virtual ~Jeans() { 
   } virtual void show() { 
    cout << "Jeans" << endl; Finery::show(); } }; int main() { 
    Person *p = new Person("小菜"); TShirts *oTShirt = new TShirts(); Jeans *oJeans = new Jeans(); oTShirt->Decorate(p); oJeans->Decorate(oTShirt); oJeans->show(); delete p; p = nullptr; delete oTShirt; oTShirt = nullptr; delete oJeans; oJeans = nullptr; return 0; } 

C

#include <stdio.h> #include <stdlib.h> #include <string.h> // Component 类型定义 typedef struct Person { 
    char *name; void (*show)(struct Person *); } Person; // Decorator 类型定义 typedef struct Finery { 
    Person base; Person *component; } Finery; // ConcreteDecorator 类型定义 typedef struct TShirts { 
    Finery base; } TShirts; typedef struct Jeans { 
    Finery base; } Jeans; // 实现 Finery 的 show 方法 void finery_show(Finery *self) { 
    if (self->component && self->component->show) { 
    self->component->show(self->component); } } // 实现 TShirts 的 show 方法 void tshirts_show(TShirts *self) { 
    printf("Tshirt\n"); finery_show((Finery *)self); } // 实现 Jeans 的 show 方法 void jeans_show(Jeans *self) { 
    printf("Jeans\n"); finery_show((Finery *)self); } // Finery 构造函数 Finery *finery_new(Person *component) { 
    Finery *self = malloc(sizeof(Finery)); self->base.show = finery_show; self->component = component; return self; } // TShirts 构造函数 TShirts *tshirts_new(Finery *component) { 
    TShirts *self = malloc(sizeof(TShirts)); self->base.base.show = tshirts_show; self->base.component = component; return self; } // Jeans 构造函数 Jeans *jeans_new(Finery *component) { 
    Jeans *self = malloc(sizeof(Jeans)); self->base.base.show = jeans_show; self->base.component = component; return self; } // ConcreteComponent 方法实现 void person_show(Person *self) { 
    printf("装扮的 %s\n", self->name); } int main() { 
    Person *p = malloc(sizeof(Person)); p->name = strdup("小菜"); p->show = person_show; Finery *oTShirt = finery_new(p); TShirts *tshirts = tshirts_new(oTShirt); Finery *oJeans = finery_new(tshirts); Jeans *jeans = jeans_new(oJeans); jeans->base.base.show(jeans); free(p->name); free(p); free(tshirts); free(oTShirt); free(jeans); free(oJeans); return 0; }