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多态实现的好奇怪，也勉强能用
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README.md
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README.md
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# cmake_demo
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#### 介绍
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{**以下是 Gitee 平台说明，您可以替换此简介**
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Gitee 是 OSCHINA 推出的基于 Git 的代码托管平台（同时支持 SVN）。专为开发者提供稳定、高效、安全的云端软件开发协作平台
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无论是个人、团队、或是企业，都能够用 Gitee 实现代码托管、项目管理、协作开发。企业项目请看 [https://gitee.com/enterprises](https://gitee.com/enterprises)}
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## CMAKE
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#### 软件架构
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软件架构说明
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## 多态
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### 多态的本质
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同样的接口，可以即实现父类的功能，也可以实现子类的功能。主要看传参的类型。
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#### 安装教程
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1. xxxx
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2. xxxx
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3. xxxx
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#### 使用说明
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1. xxxx
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2. xxxx
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3. xxxx
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#### 参与贡献
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1. Fork 本仓库
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2. 新建 Feat_xxx 分支
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3. 提交代码
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4. 新建 Pull Request
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#### 特技
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1. 使用 Readme\_XXX.md 来支持不同的语言，例如 Readme\_en.md, Readme\_zh.md
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2. Gitee 官方博客 [blog.gitee.com](https://blog.gitee.com)
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3. 你可以 [https://gitee.com/explore](https://gitee.com/explore) 这个地址来了解 Gitee 上的优秀开源项目
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4. [GVP](https://gitee.com/gvp) 全称是 Gitee 最有价值开源项目，是综合评定出的优秀开源项目
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5. Gitee 官方提供的使用手册 [https://gitee.com/help](https://gitee.com/help)
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6. Gitee 封面人物是一档用来展示 Gitee 会员风采的栏目 [https://gitee.com/gitee-stars/](https://gitee.com/gitee-stars/)
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C语言实现思路：
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因为语法不支持，因此采用特殊的方式来实现。
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| 类型 | 实现方式 | 弊端| 问题举例|
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| --- | --- | --- | --- |
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| 匿名结构体 | 指针 | 多重继承，成员可能冲突 | B->A, C->A, D->B,D->C|
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| 虚函数表 | 指针 | 子类父类必须将虚表放在结构体最开头，且不支持多继承下的多态 | |
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| 虚函数多参数 | 指针 | 继承的父类无顺序强制要求，且可以多继承。但类方法参数变多 | |
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140
main.c
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main.c
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struct _virtual_table
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{
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VIRTUAL void (*area)(void *self);
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VIRTUAL void (*draw)(void *self);
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VIRTUAL void (*area)(void *self, void *parent);
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VIRTUAL void (*draw)(void *self, void *parent);
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};
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void virtual_area(void *self)
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void virtual_area(void *self, void *parent)
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{
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ASSERT_CALL_VIRTUAL_METHOD();
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}
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void virtual_draw(void *self)
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void virtual_draw(void *self, void *parent)
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{
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ASSERT_CALL_VIRTUAL_METHOD();
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}
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@ -44,24 +44,24 @@ struct _shape
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struct _virtual_table vtb;
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};
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void shape_area(void *self)
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void shape_area(void *self, void *parent)
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{
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struct _shape *pthis = (struct _shape *)self;
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pthis->vtb.area(self);
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struct _shape *pthis = (struct _shape *)parent;
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pthis->vtb.area(self, NULL);
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}
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void shape_draw(void *self)
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void shape_draw(void *self, void *parent)
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{
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struct _shape *pthis = (struct _shape *)self;
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pthis->vtb.draw(self);
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struct _shape *pthis = (struct _shape *)parent;
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pthis->vtb.draw(self, NULL);
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}
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PRIVATE void _shape_area(void *self)
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PRIVATE void _shape_area(void *self, void *parent)
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{
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ASSERT_CALL_VIRTUAL_METHOD();
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}
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PRIVATE void _shape_draw(void *self)
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PRIVATE void _shape_draw(void *self, void *parent)
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{
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ASSERT_CALL_VIRTUAL_METHOD();
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}
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@ -74,8 +74,8 @@ struct _shape *shape_new(void)
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return NULL;
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}
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static struct _virtual_table vtb = {
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.area = (void (*)(void *self))_shape_area,
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.draw = (void (*)(void *self))_shape_draw
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.area = (void (*)(void *self, void *parent))_shape_area,
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.draw = (void (*)(void *self, void *parent))_shape_draw
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};
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shape->vtb = vtb;
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return shape;
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@ -93,9 +93,12 @@ void shape_free(struct _shape * self)
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struct _rect
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{
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int invalid;
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// super
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// struct _shape shape;
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struct _virtual_table vtb;
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struct _shape shape;
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// struct _shape;
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// struct _virtual_table vtb;
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// attribute
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double width, height;
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@ -105,12 +108,12 @@ struct _rect
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// void (*draw)(void *self);
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};
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void rect_area(struct _rect *self)
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void rect_area(struct _rect *self, void *parent)
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{
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printf("rect area = %0.2f\n", self->width * self->height);
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}
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void rect_draw(struct _rect *self)
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void rect_draw(struct _rect *self, void *parent)
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{
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printf("rect draw\n");
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}
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@ -126,19 +129,23 @@ struct _rect *rect_new(double width, double height)
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rect->height = height;
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static struct _virtual_table vtb = {
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.area = (void (*)(void *self))rect_area,
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.draw = (void (*)(void *self))rect_draw
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.area = (void (*)(void *self, void *parent))rect_area,
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.draw = (void (*)(void *self, void *parent))rect_draw
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};
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rect->vtb = vtb;
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rect->shape.vtb = vtb;
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// rect->vtb = vtb;
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return rect;
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}
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struct _circle
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{
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int invalid;
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// super
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// struct _shape shape;
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struct _virtual_table vtb;
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struct _shape shape;
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// struct _shape;
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// struct _virtual_table vtb;
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// attribute
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double radius;
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@ -148,11 +155,11 @@ struct _circle
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// void (*draw)(void *self);
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};
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void circle_area(struct _circle *self)
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void circle_area(struct _circle *self, void *parent)
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{
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printf("circle area = %0.2f\n", 3.14 * self->radius * self->radius);
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}
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void circle_draw(struct _circle *self)
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void circle_draw(struct _circle *self, void *parent)
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{
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printf("circle draw\n");
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}
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@ -167,46 +174,85 @@ struct _circle *circle_new(double radius)
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circle->radius = radius;
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static struct _virtual_table vtb = {
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.area = (void (*)(void *self))circle_area,
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.draw = (void (*)(void *self))circle_draw,
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.area = (void (*)(void *self, void *parent))circle_area,
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.draw = (void (*)(void *self, void *parent))circle_draw,
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};
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circle->vtb = vtb;
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// circle->vtb = vtb;
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circle->shape.vtb = vtb;
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return circle;
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}
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#if 0
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struct _cube
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{
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// 继承自 struct _shape
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struct _rect;
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// attibute
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double length;
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};
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void cube_area(struct _cube *self)
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{
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printf("cube area = %0.2f\n", self->length * self->length * self->length);
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}
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void cube_draw(struct _cube *self)
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{
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printf("cube draw\n");
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}
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struct _cube* cube_new(double length)
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{
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struct _cube *cube = calloc(1, sizeof(struct _cube));
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if (cube == NULL)
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{
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return NULL;
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}
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cube->length = length;
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static struct _virtual_table vtb = {
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.area = (void (*)(void *self))cube_area,
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.draw = (void (*)(void *self))cube_draw,
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};
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cube->vtb = vtb;
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return cube;
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}
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#endif
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int main(int argc, char *argv[])
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{
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struct _rect *rect = rect_new(4, 5);
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rect_area(rect);
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rect_draw(rect);
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rect_area(rect, rect);
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rect_draw(rect, rect);
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struct _circle *circle = circle_new(3);
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circle_area(circle);
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circle_draw(circle);
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circle_area(circle, circle);
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circle_draw(circle, circle);
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printf("------------------------------\n");
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shape_area(rect);
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shape_area(circle);
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shape_area(rect, &rect->shape);
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shape_draw(rect, &rect->shape);
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shape_draw(rect);
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shape_draw(circle);
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shape_area(circle, &circle->shape);
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shape_draw(circle, &circle->shape);
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printf("------------------------------\n");
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struct _shape *shape = (struct _shape *)rect_new(2,3);
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shape_area(shape);
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shape_draw(shape);
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struct _shape *shape2 = NULL;
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shape2 = (struct _shape *)circle;
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shape_area(shape2);
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shape_draw(shape2);
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struct _rect *rect2 = (struct _rect *)rect_new(2, 3);
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shape_area(rect2, &rect2->shape);
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shape_draw(rect2, &rect2->shape);
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struct _circle *circle2 = (struct _circle *)circle_new(1);
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shape_area(circle2, &circle->shape);
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shape_draw(circle2, &circle->shape);
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printf("------------------------------\n");
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struct _shape *shape3 = shape_new();
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shape_area(shape3);
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shape_draw(shape3);
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struct _shape *shape = shape_new();
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shape_area(shape, shape);
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shape_draw(shape, shape);
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return 0;
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}
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