Demonstration of poor man's try-catch construct in C99 using preprocessor macros

try-catch.c

/* Demonstration of a poor man's try-catch construct in C99 using
 * C preprocessor macros to make the syntax look vaguely like
 * try-catch constructs in other lagnuages. This implementation
 * is incredibly bad because C macros are very error prone and
 * this implementation cannot have nested try-catch constructs
 */
#include <stdio.h>
#include <assert.h>

#define TRY ;  _Pragma("pop_macro(\"EXCEPTION_EXIT_LABEL\")")
#define CATCH(L) goto EXCEPTION_EXIT_LABEL; L :
#define END_TRY_CATCH EXCEPTION_EXIT_LABEL : ;
#define RAISE(X) goto X

// Exception exit block labels (this allows at most two try catch block declarations)
// inside a function
#define EXCEPTION_EXIT_LABEL _Pragma("GCC error \"Run out of exit labels\"")
#pragma push_macro("EXCEPTION_EXIT_LABEL")
#define EXCEPTION_EXIT_LABEL exception_exit_1
#pragma push_macro("EXCEPTION_EXIT_LABEL")
#define EXCEPTION_EXIT_LABEL exception_exit_0
#pragma push_macro("EXCEPTION_EXIT_LABEL") // First push here is meant to be popped by first TRY

int main(int argc, char** argv) {
  TRY {
    printf("start\n");
    if (argc == 2)
      RAISE(bar);
    if (argc > 1)
      RAISE(foo);
  }
  CATCH(foo) {
    printf("catch foo\n");
  }
  CATCH(bar) {
    printf("catch bar\n");
  }
  END_TRY_CATCH
  printf("done0\n");

  printf("Let's try more things\n");

  TRY {
    printf("second\n");
    if (argc > 2)
      RAISE(baz);
  }
  CATCH(baz) {
    printf("catch baz\n");
  }
  END_TRY_CATCH
  return 0;
}