在这种情况下，如何实现程序的模块化和信息隐藏呢？

Question

我创建了两个 classes "DEVICE_s" 和 "DEVICE_SET_s" 如下：

Device_Manager.h

typedef struct DEVICE_s DEVICE_s;
typedef struct DEVICE_SET_s DEVICE_SET_s;

Device_Manager.c

struct DEVICE_s
{
    uint32_t IP;
    TYPE_e Type;
    METHOD_e Method;
    GROUP_RULE_e GroupRule;
    char Name[NAME_SIZE];
};
struct DEVICE_SET_s
{
    uint8_t     Total;
    uint8_t     Used;
    uint8_t     Available;
    DEVICE_s    Set[SET_SIZE];
};
DEVICE_s Instance;
DEVICE_SET_s Objects;

因为我将这两个 class 放在同一个文件中，所有操作变量 "Instance" 和 "Objects" 的函数都放在这个文件中。

我认为这种方式考虑到模块化是不好的，所以我想创建另一个源文件来单独管理class "DEVICE_SET_s"，就像：

DeviceSet_Manager.h

typedef struct DEVICE_SET_s DEVICE_SET_s;

DeviceSet_Manager.c

#include "Device_Manager.h"
#include "DeviceSet_Manager.h"
struct DEVICE_SET_s
{
    uint8_t     Total;
    uint8_t     Used;
    uint8_t     Available;
    DEVICE_s    Set[SET_SIZE];    //Oops! Incomplete Type Is Not Allowed
};

但是，对于DeviceSet_Manager.c来说，class "DEVICE_s"是不可见的（不是完整类型）。

我该如何解决这个问题？谢谢

Answer 1

这是我通常做的事情：

device.h

// insert header guards here

typedef struct DEVICE_s DEVICE_s;
struct DEVICE_s
{
   ...
};

// method declarations here
DEVICE_Init(DEVICE_s * this, ...);
DEVICE_Foo(DEVICE_s * this, ...);

device.c

#include "device.h"
// method implementations here

deviceset.h

//hguards...

#include "device.h"

typedef struct DEVICE_SET_s DEVICE_SET_s;
struct DEVICE_SET_s
{
    uint8_t     Total;
    uint8_t     Used;
    uint8_t     Available;
    DEVICE_s    Set[SET_SIZE];
};

// method declarations here
DEVICE_SET_Init(DEVICE_SET_s * this, ...);
DEVICE_SET_Foo(DEVICE_SET_s * this, ...);

deviceset.c

#include "deviceset.h"
// method implementations here

usercode.c

DEVICE_SET_s myDevices;
void func(void) {
     DEVICE_SET_Init(&myDevices, a, b, c);         
        ...
}

使用这种方法，用户有责任在使用前分配内存并调用初始化函数（=构造函数）来初始化对象。

它并没有真正给你封装，而是给了最大的分配自由度。为了使封装工作良好，它需要语言的支持。因为 C 是一开始就非常有限的语言，我不建议仅仅为了满足编程范式而添加更多限制。

Answer 2

你想要的是

的不透明类型

设备
DEVICE_SET

这对两者来说都是直接相同的方式：

header，定义
- object 结构的类型不完整。指向它的指针是不透明类型，用于处理 object 的实例并传递给其接口函数
- 接口函数的原型
实施
- 类型齐全
- 接口函数

headers

device.h

#ifndef DEVICE_H
#define DEVICE_H

struct device;

struct device * device_new(void);
void device_delete(struct device *);

#endif

device_set.h:

#ifndef DEVICE_H
#define DEVICE_H

#include "device.h"

struct device_set;

struct device_set * device_set_new(size_t);
void device_set_delete(struct device_set *);

int device_set_set_device(struct device_set *, size_t, struct device *);
struct device * device_set_get_device(struct device_set *, size_t); 


#endif

实现

device.c

#include "device.h"

struct device {
  ...
};

struct device * device_new(void)
{
  struct device * pd = malloc(sizeof * pd);
  if (NULL != pd)
  {
    /* Init members here. */
  }

  return pd;
}

void device_delete(struct device * pd)
{
  if (pd)
  {
    /* de-init (free?) members here. */
  }

  free(pd);
}

device_set.c:

#include "device_set.h"

struct device_set
{
  size_t total;
  size_t used;
  size_t available; /* what is this for? isn't it just total - used? */
  struct device ** pd;
}

struct device_set * device_set_new(size_t nb)
{
  struct device_set pds = malloc(sizeof *pds);
  if (NULL != pds)
  {
    pds->pd = malloc(nb * sizeof *pds->pd);
    if (NULL == pds->pd)
    {
      free(pds);
      pds = NULL;
    }
    else
    {
      for (size_t d = 0; d < nb; ++d)
      {
        pds->pd[d] = NULL;
      }

      pds->total = nb;
      pds->used = 0;
      pds->available = 0;
    }
  }

  return pds;
}

void device_set_delete(struct device_set * pds)
{
  if (pds)
  {
    free(pds->pd);
    free(pds)
  }

  return;
}

int device_set_set_device(struct device_set * pds, size_t d, struct device * pd)
{
  int result = 0;

  if (pds->total <= d)      
  {
    result = ERANGE;
  }
  else
  {
    pds->pd[d] = pd;
  }

  return;
}    

struct device * device_set_get_device(struct device_set * pds, size_t d); 
  int result = 0;
  struct device * pd = NULL;

  if (pds->total <= d)      
  {
    result = ERANGE;
  }
  else
  {
    pd = pds->pd[d];
  }

  return pd;
}

在这种情况下，如何实现程序的模块化和信息隐藏呢？

In this case, how to modularize program as well as achieving information hiding?

c

oop

encapsulation

information-hiding

opaque-pointers

headers

实现