C23 和 C++同时用的头文件, decltype 的部份应该使用 typeof 还是 macro 换个壳? - V2EX
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C23 和 C++同时用的头文件, decltype 的部份应该使用 typeof 还是 macro 换个壳?

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  •   cnbatch May 19, 2024 2694 views
    This topic created in 749 days ago, the information mentioned may be changed or developed.

    C++11 有decltype,C23 有typeof,如果同一个头文件需要同时给 C23 和 C++使用,那么需要自动推导类型的语句应该怎么选?

    是应该加设一个 macro 分开处理?对于 C23 就用 typeof ,对于 C++就用 decltype 。
    又或者在 C23 环境用#define把 decltype 替换成 typeof ?

    然后还有typeof_unqual,C++是用模板的形式来做的,没记错的话应该等价于std::remove_cv_t<decltype(var)>,是不是只能用 macro 分开处理了?

    Supplement 1    May 19, 2024
    发这帖子是想看看有没有办法,尽量避免把同一条语句写两遍
    4 replies    2024-05-20 01:57:53 +08:00
    ysc3839
        1
    ysc3839  
       May 19, 2024
    #ifdef __cplusplus
    cnbatch
        2
    cnbatch  
    OP
       May 19, 2024
    @ysc3839 肯定会用到这条,主要是,后边的写法如何尽量精简

    比如
    #ifdef __cplusplus
    THIS_IS_MACRO(x, y) call_function(x, decltype(x)y)
    #else
    THIS_IS_MACRO(x, y) call_function(x, typeof(x)y)
    #endif

    虽然没毛病,但以后要改的话就要两个同时改,不是很方便
    agagega
        3
    agagega  
       May 20, 2024
    直接用 GCC 的__typeof__扩展(如果你确信只会用 GCC 或者 Clang 编译的话): https://gcc.gnu.org/onlinedocs/gcc/Typeof.html
    ysc3839
        4
    ysc3839  
       May 20, 2024
    @cnbatch 个人觉得没必要精简,该怎么写就怎么写,甚至可以考虑分多文件然后 include
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