c语言实现defer

Posted 2023-06-20 Tifa-Best

#define __DEFER_CONCAT_IMPL__(s1, s2) s1##_##s2
#define __DEFER_CONCAT__(s1, s2) __DEFER_CONCAT_IMPL__(s1, s2)

#if defined(__llvm__)
static inline void __defer_cleanup__(void (^*b)(void))  (*b)(); 
#define DEFER(expr) __attribute__((cleanup(__defer_cleanup__))) void (^__DEFER_CONCAT__(_DEFER_VAR_, __LINE__))(void) = ^ expr; 
#elif defined(__GNUC__)
#define DEFER(expr)                                           \\
    void __DEFER_CONCAT__(_DEFER_FUNC_, __LINE__)()  expr;  \\
    int __DEFER_CONCAT__(_DEFER_VAR_, __LINE__) __attribute__((cleanup(__DEFER_CONCAT__(_DEFER_FUNC_, __LINE__))))
#else
#error "platform not support!"
#endif

#include <stdio.h>
int main(int argc, char **argv)

#if defined(__llvm__)
    printf("llvm\\n");
#elif defined(__GNUC__)
    printf("GNUC\\n");
#else
    printf("other\\n");
#endif

    
        printf("begin of scope\\n");

        DEFER(printf("call defer1\\n"));
        DEFER(printf("call defer2\\n"));

        printf("end of scope\\n");
    
    printf("before return\\n");
    return 0;
    printf("after return\\n");

gcc test.c -o test && ./test

clang -g -fblocks test.c -o test -lBlocksRuntime && ./test

您需要使用块链接哪些库来进行clang程序

Using the cleanup variable attribute in GCC

defer 关键字在 C/C++ 上的实现方案

Emulating "defer" in C, with Clang or GCC+Blocks