c++ - 显式 C++ 宏扩展

Question

我想让所有日志记录函数都包含文件和行，因此我需要一个宏。宏定义如下:

 inline void _internLogFunc(int line, const char* function, const char* data ...)
    {...}

    #define _InternLogParams(...) _internLogFunc(__LINE__, __FUNC__, __VA_ARGS__)

    #define Log(...) _InternLogParams(__VA_ARGS__)

问题是当函数以下列方式被调用时:

 Log("[Version]: "
    #if defined(_RELEASE)
                "RELEASE "
    #elif defined(_PROFILE)
                "PROFILE "
    #else
                "DEBUG "
    #endif

    #if defined(PURE_CLIENT)
                "PURE CLIENT"
    #elif (DEDICATED_SERVER)
                "DEDICATED SERVER"
    #else
                "DEVELOPMENT BUILD"
    #endif
                );

宏展开如下:

> _internLogFunc(950,  
>                __FUNCTION__  , 
>                "[Version]: " 
>                #if defined(_RELEASE) "RELEASE "
>                #elif defined(_PROFILE) "PROFILE " 
>                #else "DEBUG " 
>                #endif 
>                #if defined(PURE_CLIENT) "PURE CLIENT" 
>                #elif (DEDICATED_SERVER) "DEDICATED SERVER" 
>                #else "DEVELOPMENT BUILD" 
>                #endif);

有谁知道如何让作为参数给出的宏首先展开？

Answer 1

只需将所有 #ifedf 放在函数调用之外，并使用它们来定义一些文字字符串。示例:

#ifdef _RELEASE 
#define VERSION "RELEASE"
#else 
#define VERSION "DEBUG"
#endif

...

LOG(VERSION);    

...