c++ - 避免 if else 打印 block 中的代码重复

Question

我讨厌这里的代码重复。如何使它更简洁？重复文本的另一个宏是个好主意吗？我有一种奇怪的感觉，我也遗漏了一些非常明显的东西。

      #define CHECK(para_1, para_2, para_3, epic_fail) { \
      if (para_2 != para_3) { \
        size_t __bytes; \
        if(#para_1 == "special") { \
          __bytes = snprintf( \
            NULL, 0, \
            #para_1 \
              " this_thing '%s'(%p) doesn't go well with special this_thing '%s'(%p)", \
            para_2, para_2, para_3, para_3); \
        } else { \
          __bytes = snprintf( \
            NULL, 0, \
            #para_1 " this_thing '%s'(%p) doesn't go well with unique_goldfish this_thing '%s'(%p)", \
            para_2, para_2, para_3, para_3); \
        } \
        char * message = \
          reinterpret_cast<char *>(rmw_allocate(__bytes + 1)); \
        if(#para_1 == "special") { \
          snprintf( \
            message, __bytes + 1, \
            #para_1 \
              " this_thing '%s'(%p) doesn't go well with special this_thing '%s'(%p)", \
            para_2, para_2, para_3, para_3); \
        } else{ \
          snprintf( \
            message, __bytes + 1, \
            #para_1 " this_thing '%s'(%p) doesn't go well with unique_goldfish this_thing '%s'(%p)", \
            para_2, para_2, para_3, para_3); \
        } \
        SET_THE_ERROR(message); \
        free_the_mem(message); \
        epic_fail; \
      } \
    }

Answer 1

在宏中使用宏:

#define CHECK_PRINT(n) snprintf( \
    message, __bytes + n, \
    #para_1 " this_thing '%s'(%p) doesn't go well with unique_goldfish this_thing '%s'(%p)", \
    para_2, para_2, para_3, para_3); 

#define CHECK(para_1, para_2, para_3, epic_fail) { \
    if (para_2 != para_3) { \
        size_t __bytes; \
        if(#para_1 == "special") { \
          __bytes = CHECK_PRINT(n); \
        } else { \
          __bytes = CHECK_PRINT(n); \
        } \
       ...