用C语言实现面向对象程序设计(一)

许多朋友都知道用C语言是可以实现面向对象程序设计的，但是具体到操作的细节部分就有些茫然不知所措了。为此作者在研究LW_OOPC的基础上，对其进行充分的简化，只保留最基本的面向对象功能，形成自己的OOSM宏包，其实这些东西已经够用了，以下是OOSM宏包的源代码：

/*
    Object-Oriented Support Macros(OOSM)

    OOSM is an object-oriented support macros, it makes the C programming language
    with object-oriented programming capabilities.

    LW_OOPC(http://sourceforge.net/projects/lwoopc/) means
    Light-weight Object-Oriented Programming in C, written by MISOO team,
    it is a very outstanding works!

    OOSM inherits the essence of LW_OOPC and crops to retain the basic features.
    OOSM written by Turingo Studio,
    but anyone can copies modifies, and distributes it freely.

    Hansome Sun(hansome.sun@gmail.com)
    January 18, 2013
*/
#ifndef __OOSM_H__
#define __OOSM_H__

#include <stdlib.h>

#define class(type)                     \
    typedef struct type type;           \
    type* type##_new(void);             \
    void type##_constructor(type* t);   \
    int type##_destructor(type* t);     \
    void type##_delete(type* t);        \
    struct type

#define interface(type)                 \
    typedef struct type type;           \
    struct type

#define extends(type)       type type
#define implements(type)    type type

#define constructor(type)                   \
    type* type##_new(void)                  \
    {                                       \
        type* this;                         \
        this = (type*)malloc(sizeof(type)); \
        if(this == NULL)    return NULL;    \
        type##_constructor(this);           \
        return this;                        \
    }                                       \
                                            \
    void type##_constructor(type* this)

#define destructor(type)                            \
    void type##_delete(type* this)                  \
    {                                               \
        if(type##_destructor(this))    free(this);  \
    }                                               \
                                                    \
    int type##_destructor(type* this)

#define mapping(tf, sf) this->tf = sf

#endif/*__OOSM_H__*/

真正的代码不到30行，大家可以直观的意识到用C语言实现面向对象的代价其实是非常低的。在OOSM宏包的支持下，C语言的代码可以如此的优雅紧凑：

#include <stdio.h>
#include "imeas.h"
#include "ccirc.h"
#include "crect.h"
#include "csqua.h"

int main(int argc, char* argv[])
{
    ccirc* c = ccirc_new();
    crect* r = crect_new();
    csqua* s = csqua_new();

    c->radius = 9.23;
    r->width = 23.09;
    r->height = 78.54;
    s->crect.width = 200.00;
    printf("Circle: (%lf, %lf, %lf)\n", c->diam(c), c->imeas.peri(c), c->imeas.area(c));
    printf("Rectangle: (%lf, %lf)\n", r->imeas.peri(r), r->imeas.area(r));
    printf("Square: (%lf, %lf)\n", s->crect.imeas.peri(s), s->crect.imeas.area(s));

    ccirc_delete(c);
    crect_delete(r);
    csqua_delete(s);
    return 0;
}

那么ccirc/crect/csqua等对象是如何描述的呢，请看下集分解。