C语言实现OOP 版本3 ：简化代码

我倒是不追求代码和C++相似，但是应该追求简洁的代码，下面是一个新的尝试

---

shape.h

#ifndef SHAPE_H
#define SHAPE_H

typedef struct shape_t 
{
    void *shapeData;
    void (*area)(void *);
    void (*release)(void *);
}Shape;

void release(void *shape);

#endif

shape.c

#include <stdlib.h>
#include "shape.h"

void release(void *shape)
{
    free(((Shape*)shape)->shapeData);
    free(shape);
}

circle.h

#ifndef CIRCLE_H
#define CIRCLE_H

#include "shape.h"

typedef struct 
{
    double r;
}Circle;

Shape* makeCircle(double r);

#endif

circle.c

#include <assert.h>
#include <stdlib.h>
#include <stdio.h>
#include "shape.h"
#include "circle.h"

const double PI = 3.14159;

static void area(void *shape)
{
    Circle *_circle = (Circle*)((Shape *)shape)->shapeData;
    printf("the circle area is %f 
", _circle->r * _circle->r * PI);
}

Shape* makeCircle(double r)
{
    Shape *shape = (Shape *)malloc(sizeof(Shape));
    Circle *circle = (Circle *)malloc(sizeof(Circle));
    assert(shape != NULL && circle != NULL);
    assert(r > 0);

    circle->r = r;
    shape->shapeData = circle;
    shape->area = &area;
    shape->release = &release;

    return shape;
}

rectange.h

#ifndef RECTANGLE_H
#define RECTANGLE_H

typedef struct{
    float x;
    float y;
}Rectangle;


Shape *makeRectangle(float x, float y);
#endif

rectange.c

#include <assert.h>
#include <stdlib.h>
#include <stdio.h>
#include "shape.h"
#include "rectangle.h"

static void area(void *shape)
{
    Rectangle *rectangle = (Rectangle*)((Shape *)shape)->shapeData;
    printf("the rectangle area is %f 
", rectangle->x * rectangle->y);
}

Shape* makeRectangle(float x, float y)
{
    Shape *shape = (Shape *)malloc(sizeof(Shape));
    Rectangle *rectangle = (Rectangle *)malloc(sizeof(Rectangle));
    assert(shape != NULL && rectangle != NULL);
    assert(x > 0 && y > 0);

    rectangle->x = x;
    rectangle->y = y;
    shape->shapeData = rectangle;
    shape->area = &area;
    shape->release = &release;

    return shape;
}

main.c

#include <stdio.h>
#include "shape.h"
#include "circle.h"
#include "rectangle.h"

void printShapeArea(Shape **shapes,int length)
{
    int i=0;
    for(i=0;i<length;i++)
    {
        Shape *shape = shapes[i];
        shape->area(shape);
        shape->release(shape);
    }
}

int main()
{
    Shape *p[3] = {makeCircle(3.2),makeCircle(3.2),makeRectangle(3,4)};
    printShapeArea(p,3);
    return 0;
}