C语言实现OOP 版本2

写版本2的原因，还是发现在不同的具体图形模块里发现了重复的release代码，这是坏味道，所以还是决定消除这些重复代码，DRY！

---

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

typedef struct
{
    double r;
}CircleData;

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

Circle *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;
    CircleData* data = (CircleData*)_circle->shapeData;
    printf("the circle area is %f \n", data->r * data->r * PI);
}

/*
static void release(void *shape)
{
    Circle *_circle = (Circle *)shape;
    CircleData* data = (CircleData*)_circle->shapeData;
    free(data);
    free(_circle);
}
*/

Circle *makeCircle(double r)
{
    CircleData* circleData = (CircleData*)malloc(sizeof(CircleData));
    Circle* circle = (Circle*)malloc(sizeof(Circle));
    assert(circleData != NULL);
    assert(circle != NULL);
    assert(r > 0);

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

    return circle;
}

square.h

#ifndef SQUARE_H
#define SQUARE_H

typedef struct
{
    double x;
    double y;
}SquareData;

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

Square *makeSquare(double x, double y);

#endif

square.c

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

static void area(void *shape)
{
    Square *square = (Square *)shape;
    SquareData* data = (SquareData*)square->shapeData;
    printf("the square area is %f \n", data->x * data->y);
}

/*
static void release(void *shape)
{
    Square *square = (Square *)shape;
    SquareData* data = (SquareData*)square->shapeData;
    free(data);
    free(square);
}
*/

Square *makeSquare(double x, double y)
{
    SquareData* squareData = (SquareData*)malloc(sizeof(SquareData));
    Square* square = (Square*)malloc(sizeof(Square));
    assert(squareData != NULL);
    assert(square != NULL);
    assert(x > 0 && y > 0);

    squareData->x = x;
    squareData->y = y;
    square->shapeData = squareData;
    square->area = &area;
    square->release = &release;

    return square;
}

main.c 发现没有，尽管内部进行了调整，这些的代码丝毫没变！重构就应该这样，内部的调整不太涉及到client代码，除非真的决定修改接口，修改接口内部应该优先于调整接口

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

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

int main()
{
    Shape *p[3] = {(Shape*)makeCircle(3.2),(Shape*)makeCircle(3.2),(Shape*)makeSquare(3.1,4)};
    printShapeArea(p,3);
    return 0;
}