DEFER.h

DEFER macros in C

DEFER.h defines 3 macros to use:

DEFER_START(N): Creates a defer scope with N possible defers.
DEFER_END(): Used to end a defer scope (before each return or exit), as this calls all the defers added since DEFER_START.
DEFER(...): Defers the code inside the brackets to DEFER_END.

int main() {
  DEFER_START(2);

  int x = 68;
  if (x) {
    DEFER_START(2);

    DEFER(fputc('\n', stdout));
    DEFER(printf("%i", x));
    ++x;

    DEFER_END();
  }

  DEFER(printf("world!"); fputc('\n', stdout));
  DEFER(printf("Hello, "));

  DEFER_END();
}

69
Hello, world!

The implementation uses an array of jmp_bufs (or addresses of labels in the case of GNU C supporting compilers) to allow unwinding of the defers accumulated and then proceed with control flow like normal.

Psteven5/DEFER.h

DEFER.h