我有一个标题和.cpp文件(称之为Foo.h / .cpp),其结构如下(为简单起见省略了几个不相关的细节):
foo.h中
#include <boost/bimap.hpp>
const std::string & ToHeader(const int msgID);
int ToMsgID(const std::string & msgHdr);
typedef boost::bimap<int, std::string> MsgIDBimap;
MsgIDBimap & GetMessageIDToStringMap();
Foo.cpp中
#include "Foo.h"
#include <boost/assign/list_of.hpp>
static MsgIDBimap msgIDBimap = boost::assign::list_of<MsgIDBimap::relation>
((int)ROM_MSG, "")
... // a whole bunch of other entries
; // end static bimap initialization
const std::string & ToHeader(const int msgID)
{
MsgIDBimap::left_iterator foundIT = msgIDBimap.left.find(msgID);
if(foundIT != msgIDBimap.left.end()) // found
{
return foundIT->second;
}
throw std::string("MSG_ID_NOT_FOUND");
}
int ToMsgID(const std::string & msgHdr)
{
int msgID = (int)MSG_UNKNOWN; // unknown message header
MsgIDBimap::right_iterator foundIT = msgIDBimap.right.find(msgHdr);
if(foundIT != msgIDBimap.right.end()) // found
{
msgID = foundIT->second;
}
return msgID;
}
MsgIDBimap & GetMessageIdToStringMap()
{
return msgIDBimap;
}
问题是现在我需要支持不支持bimap的早期版本的boost(很糟糕,我知道......但我别无选择)。到目前为止,这是我的解决方案:
foo.h中
#include <boost/version.hpp>
#define BOOST_VER_MAJOR (BOOST_VERSION/100000) // ex.: 1 in 1_37_0
#define BOOST_VER_MINOR ((BOOST_VERSION/100) % 1000) // ex.: 37 in 1_37_0
#define BOOST_VER_PATCH (BOOST_VERSION % 100) // ex.: 0 in 1_37_0
/*************************************************************************************************/
#if ((BOOST_VER_MAJOR >= 1) && (BOOST_VER_MINOR >= 35)) // boost greater than or equal to 1.35 (bimap available)
#include <boost/bimap.hpp>
#endif
/*************************************************************************************************/
const std::string & ToHeader(const int msgID);
int ToMsgID(const std::string & msgHdr);
/*************************************************************************************************/
#if ((BOOST_VER_MAJOR >= 1) && (BOOST_VER_MINOR >= 35)) // boost greater than or equal to 1.35 (bimap available)
typedef boost::bimap<int, std::string> MsgIDBimap;
MsgIDBimap & GetMessageIdToStringMap();
#endif
/*************************************************************************************************/
Foo.cpp中
#include "Foo.h"
#include <boost/assign/list_of.hpp>
#if ((BOOST_VER_MAJOR >= 1) && (BOOST_VER_MINOR >= 35)) // boost greater than or equal to 1.35 (bimap available)
static MsgIDBimap msgIDBimap = boost::assign::list_of<MsgIDBimap::relation>
((int)ROM_MSG, "") // <ROM message> (no header)
; // end static msgIDBimap initialization
const std::string & ToHeader(const int msgID)
{
MsgIDBimap::left_iterator foundIT = msgIDBimap.left.find(msgID);
if(foundIT != msgIDBimap.left.end()) // found
{
return foundIT->second;
}
throw std::string("MSG_ID_NOT_FOUND");
}
int ToMsgID(const std::string & msgHdr)
{
int msgID = (int)MSG_UNKNOWN; // unknown message header
MsgIDBimap::right_iterator foundIT = msgIDBimap.right.find(msgHdr);
if(foundIT != msgIDBimap.right.end()) // found
{
msgID = foundIT->second;
}
return msgID;
}
MsgIDBimap & GetMessageIdToStringMap()
{
return msgIDBimap;
}
/*************************************************************************************************/
#else // boost less than 1.35, bimap not available
typedef std::map<int, std::string> MsgIDToStringMap;
static MsgIDToStringMap msgIDToStringMap = boost::assign::map_list_of<int, std::string>
((int)ROM_MSG, "") // <ROM message> (no header)
; // end static msgIDToStringMap initialization
const std::string & ToHeader(const int msgID)
{
const MsgIDToStringMap::const_iterator foundIT = msgIDToStringMap.find(msgID);
if(foundIT != msgIDToStringMap.end()) // found
{
return foundIT->second;
}
throw std::string("MSG_ID_NOT_FOUND");
}
#define FLIP_ARGS(x,y) (y,x)
typedef std::map<std::string, int> StringToMsgIDMap;
static StringToMsgIDMap stringToMsgIDMap = boost::assign::map_list_of<std::string, int>
FLIP_ARGS((int)ROM_MSG, "") // <ROM message> (no header)
; // end static stringToMsgIDMap initialization
int ToMsgID(const std::string & msgHdr)
{
int msgID = (int)MSG_UNKNOWN; // unknown message header
const StringToMsgIDMap::const_iterator foundIT = stringToMsgIDMap.find(msgHdr);
if(foundIT != stringToMsgIDMap.end()) // found
{
msgID = foundIT->second;
}
return msgID;
}
#endif
虽然这有效,但问题是GetMessageIDToStringMap()函数声明/定义仅存在于后面的升级版本场景中(两个场景彼此不是100%一致)。我知道早期的升级版本场景不会需要GetMessageIDToStringMap()函数本身。
理想情况下,我想将静态bimap保留在.cpp文件中,并将GetMessageIDToStringMap()移动到某个地方,以便Foo.h / .cpp对每个#ifdef块100%一致。问题是bimap是.cpp文件中的静态变量,没有其他文件可以访问它。即使我将bimap设为全局变量而不是静态变量,我现在必须在头文件中公开一个全局变量,这个变量只会出现在更高版本的boost中。
有没有办法解决这个问题,以便文件的两个版本(boost&gt; = 1.35与之前的boost相比)总是100%相互一致,但GetMessageIDToStringMap()函数在另一个文件中可用?
答案 0 :(得分:0)
回应问题中的评论:
在foo.cpp中:
typedef std::map<int, std::string> MsgIDToStringMap;
//you can remove the static
MsgIDToStringMap msgIDToStringMap = ...
现在在other.cpp文件中:
extern MsgIDToStringMap msgIDToStringMap;
//and you can use the global variable.
但正如我在第一条评论中所说的,我更喜欢单身课程。