相互依赖的类声明 [英] Mutually Dependent class declarations

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本文介绍了相互依赖的类声明的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

 在文件中包含了这个编译错误的意思，我希望我能解释一下。从sys / charon.cpp：4：0：

并以黄色下划线：

  #include../headers/charon.h

同样，在头文件charon.h中定义的类型标识符charon_不同的错误。

  sys /../ headers / charon.h：17：9：error：redefinition' ：charon_'
 sys /../ headers / chio.h：86：9：error：以前的'class charon :: charon_'定义
 sys / charon.cpp：12：20：定义的隐式声明的'charon :: charon _ :: charon_（）'

但是我希望他们所有相关的第一个错误，我认为这是与我想做的事情有关。

  //文件1.h 
 / ********** / 
 class I 
 {
 private：
 B * my_private_b; 
 
 public：
 I（B& handle）;不幸的是，我需要'B'之前'文件1'开始定义'I' '..但同时，我需要我定义为B.所以我不知道如何定义两个之前的其他..我猜我需要一个更先进的解决方案，但我不知道。 / p> 
 
 
  //档案2.h 
 / *********** / 
 class B 
 {
 private：
 I i; 
 O o; 
 
 public：
 B（）; 
} 
  
所以如果我能找到答案，这下一部分为我自己。如果你认为检查我是否正确的方向，我会粘贴所有的代码在下面。
 
 
 
。＃。＃。＃ 。＃。＃。＃。＃。＃。＃。＃。＃。＃。＃。＃。＃。＃。＃。＃。＃。＃。＃。。＃。＃。＃。＃。
 
 
 
不够长，没有阅读吗？ 
这里是所有的行，除了注释，来自所有四个文件的代码。按感知的重要性顺序。
  //////////////////// //////////////////// 
 ///// 
 ///////////// 
 // /// 
 ///// 
 ///// 
 //文件：chio.h 
 
 #ifndef CHIO_H 
 #define CHIO_H 
 #include< deque> 
 #include< queue> 
 #include< iostream> 
 
 using namespace std; 
 
 namespace charon 
 {
 class charon_ 
 {
 
}; 
} 
命名空间chio 
 {
 class chout_ 
 {
 private：
 
 public：
 chout_ ; 
〜chout_（）; 
}; 
 
 class chin_ 
 {
 private：
 charon :: charon_ * engine; 
 
 public：
 chin_（charon :: charon_& handle）; 
 chin_（）; 
〜chin_（）; 
}; 
} 
 
 #endif / * CHIO_H * / 
 
 ////////////////////// //////////////// 
 ///// 
 ///////////// 
 //// / 
 ///// 
 ///// 
 //文件：charon.h / * 
 // 
 *文件：charon.h 
 *作者：josh 
 * 
 *创建日期：2012年4月11日，22:26 
 * / 
 
 #ifndef CHARON_H 
 #define CHARON_H 
 //＃includeboost / thread.hpp
 #includechio.h
 
 using namespace std; 
 using namespace chio; 
 namespace charon 
 {
 class charon_ {
 private：
 chout_ engine_output; 
 chin_engine_input; 
 // boost :: thread input_thread; 
 // boost :: thread output_thread; 
 void start_threads（）; 
 void stop_threads（）; 
 
 public：
 charon_（）; 
 charon_（charon_& orig）; 
〜charon_（）; 
 void run（）; 
}; 
} 
 
 
 #endif / * CHARON_H * / 
  
这些是构造函数/ cpp文件。
  charon.cpp 
 #include< iostream> 
 //＃include< boost / thread.hpp> 
 //＃include< boost / date_time.hpp> 
 #include../headers/charon.h
 
 using namespace std; 
 using namespace charon; 
 using namespace chio; 
 
 namespace charon 
 {
 charon _ :: charon _（）{
 engine_input = chio :: chin _（（charon _ *）this）; 
} 
}; 
 
 //^^charon.cpp^^ 
 --------- 
 //chin.cpp 
 
 #include< ; iostream> 
 #include< borland / conio.h> 
 #include< ncurses.h> 
 #include< deque> 
 #include../headers/charon.h
 
 using namespace std; 
 using namespace charon; 
 using namespace chio; 
命名空间chio 
 {
 chin _ :: chin_（charon :: charon_& handle）{
 engine = handle; 
} 
 chin _ ::〜chin_（）{
} 
} 
  
 
 b $ b 
对于结局，我个人讨厌阅读，所以我一直在推迟只是问这一切的任何人。因此，如果你已经到这里，你可能也想要这个太。
 / usr / bin / gmake-f nbproject / Makefile -Debug.mk QMAKE = SUBPROJECTS = .build-conf 
 gmake [1]：输入目录`/ home / josh / Projects / Maze / Charon'
/ usr / bin / gmake /Makefile-Debug.mk dist / Debug / GNU-Linux-x86 / charon 
 gmake [2]：输入目录`/ home / josh / Projects / Maze / Charon'
 mkdir -p build / Debug / GNU-Linux-x86 / sys 
 rm -f build / Debug / GNU-Linux-x86 / sys / charon.od 
 g ++ -c -g -MMD -MP -MF build / Debug / GNU -Linux-x86 / sys / charon.od -o build / Debug / GNU-Linux-x86 / sys / charon.o sys / charon.cpp 
从sys / charon.cpp：4： 
 sys /../ headers / charon.h：17：9：error：redefinition'class charon :: charon_'
 sys /../ headers / chio.h：86：9：error ：前面定义的'charon :: charon_'
 sys / charon.cpp：12：20：error：定义隐式声明的'charon :: charon _ :: charon_（）'
 gmake [2 ]：*** [build / Debug / GNU-Linux-x86 / sys / charon.o]错误1 
 gmake [2]：离开目录`/ home / josh / Projects / Maze / Charon'
 gmake [1]：*** [.build-conf]错误2 
 gmake [1]：离开目录`/ home / josh / Projects / Maze / Charon'
 gmake：*** [ .build-impl]错误2 
  
 
 
我会很高兴有一个更简单的版本的答案。我已经用尽了想法来修复编译错误，我已经翻转了我的巨大的C ++参考，验证我可以想到的一切。所有的语法看起来是正确的，我认为这是我还没有专门学习如何操作编译器来做这样的事情。
 
 
 
我不知道，我现在可能只是漫步。 
解决方案
它似乎在 File1。 h   B 的向前声明就足够了，而不是包含它，因为你只使用引用和指针 B 。添加：
  B类; //<< B的转发声明
 
 class I 
 {
 private：
 B * my_private_b; 
 
 public：
 I（B& handle）; 
} 
  
开头 File1.h  
 
I am trying to figure out what this compile error means, and I hope I explain this well.
In file included from sys/charon.cpp:4:0:

Following this takes me to that ^ file above, and underlines in yellow this:
#include "../headers/charon.h"

As well the type identifier "charon_", which is a class defined within the header file charon.h, is also underlined in yellow possibly a different error.
sys/../headers/charon.h:17:9: error: redefinition of ‘class charon::charon_’
sys/../headers/chio.h:86:9: error: previous definition of ‘class charon::charon_’
sys/charon.cpp:12:20: error: definition of implicitly-declared ‘charon::charon_::charon_()’

However I hope they are all related to the first error, I think it is related to something I am trying to do.
//File 1.h
/**********/
class I
{
private:
B* my_private_b;

public:
I(B& handle);
}

Unfortunately I need 'B' declared before 'file 1' begins defining 'I'.. yet at the same time, I need I to be defined for B. So I don't know how to define both before the other.. I am guessing I need a more advanced solution but I don't know.
//File 2.h
/***********/
class B
{
private:
I i;
O o;

public:
B();
}

So if I can find an answer to that, then maybe I could just check this next part for myself. If you think it would be good to check to see if I am going in the right direction I will paste all the code in question below.



.#.#.#.#.#.#.#.#.#.#.#.#.#.#.#.#.#.#.#.#.#.#.#.#.#.#.



Not Long Enough, Didn't Read?
Well here are all the lines, except for the comments, of code from all four files. In order of perceived importance.
//////////////////////////////////////
/////
/////////////
/////
/////
/////
//File: chio.h

#ifndef CHIO_H
#define CHIO_H
#include <deque>
#include <queue>
#include <iostream>

using namespace std;

namespace charon
{
  class charon_
  {

  };
}
namespace chio
{ 
  class chout_
  {
  private:

  public:
    chout_();
    ~chout_();
  };

  class chin_
  {
  private:
    charon::charon_* engine;

  public:
    chin_(charon::charon_& handle);
    chin_();
    ~chin_();
  };
}

#endif  /* CHIO_H */

//////////////////////////////////////
/////
/////////////
/////
/////
/////
//File: charon.h/* 
//
 * File:   charon.h
 * Author: josh
 *
 * Created on 11 April 2012, 22:26
 */

#ifndef CHARON_H
#define CHARON_H
//#include "boost/thread.hpp"
#include "chio.h"

using namespace std;
using namespace chio;
namespace charon
{
  class charon_ {
  private:
    chout_ engine_output;
    chin_ engine_input;
    //boost::thread input_thread;
    //boost::thread output_thread;
    void start_threads();
    void stop_threads();

  public:
    charon_();
    charon_(charon_ &orig);
    ~charon_();
    void run();
  };
}


#endif  /* CHARON_H */

These are the constructors / cpp files.
charon.cpp
#include <iostream>
//#include <boost/thread.hpp>
//#include <boost/date_time.hpp>
#include "../headers/charon.h"

using namespace std;
using namespace charon;
using namespace chio;

namespace charon
{
  charon_::charon_(){
    engine_input = chio::chin_((charon_*)this);
  }
};

//^^charon.cpp^^
---------
//chin.cpp

#include <iostream>
#include <borland/conio.h>
#include <ncurses.h>
#include <deque>
#include "../headers/charon.h"

using namespace std;
using namespace charon;
using namespace chio;
namespace chio
{
  chin_::chin_(charon::charon_& handle) {
    engine = handle;
  }
  chin_::~chin_() {
  }
}

And for the finale, I personally hate reading so I've been putting off just asking all this of anybody. So if you have come this far you probably want this too.
"/usr/bin/gmake" -f nbproject/Makefile-Debug.mk QMAKE= SUBPROJECTS= .build-conf
gmake[1]: Entering directory `/home/josh/Projects/Maze/Charon'
"/usr/bin/gmake"  -f nbproject/Makefile-Debug.mk dist/Debug/GNU-Linux-x86/charon
gmake[2]: Entering directory `/home/josh/Projects/Maze/Charon'
mkdir -p build/Debug/GNU-Linux-x86/sys
rm -f build/Debug/GNU-Linux-x86/sys/charon.o.d
g++    -c -g -MMD -MP -MF build/Debug/GNU-Linux-x86/sys/charon.o.d -o build/Debug/GNU-Linux-x86/sys/charon.o sys/charon.cpp
In file included from sys/charon.cpp:4:0:
sys/../headers/charon.h:17:9: error: redefinition of ‘class charon::charon_’
sys/../headers/chio.h:86:9: error: previous definition of ‘class charon::charon_’
sys/charon.cpp:12:20: error: definition of implicitly-declared ‘charon::charon_::charon_()’
gmake[2]: *** [build/Debug/GNU-Linux-x86/sys/charon.o] Error 1
gmake[2]: Leaving directory `/home/josh/Projects/Maze/Charon'
gmake[1]: *** [.build-conf] Error 2
gmake[1]: Leaving directory `/home/josh/Projects/Maze/Charon'
gmake: *** [.build-impl] Error 2

I would be simply glad to have an answer to my simpler version. I have run out of ideas to fix the compile errors and I have flipped through my huge C++ reference verifying everything I can think of. All the syntax looks to be correct, I think it is just that I have yet to specifically learn how to manipulate the compiler to do things like this.



I don't know, I am probably just rambling now. This has been frustrating me for the last 3 days at least.
 解决方案 
It seems like in File1.h a forward declaration of B would suffice instead of including it since you're only using references and pointers to B. Add:
class B; // << Forward declaration of B

class I
{
private:
B* my_private_b;

public:
I(B& handle);
}

at the beginning of File1.h


                        
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