text: #include <assert.h>
  #include <stdio.h>
  #include <string.h>
  
  #include "json.h"
  #include "printbuf.h"
  
  struct myinfo {
  	int value;
  };
  
  static int freeit_was_called = 0;
  static void freeit(json_object *jso, void *userdata)
  {
  	struct myinfo *info = userdata;
  	printf("freeit, value=%d\n", info->value);
  	// Don't actually free anything here, the userdata is stack allocated.
  	freeit_was_called = 1;
  }
  static int custom_serializer(struct json_object *o,
  					struct printbuf *pb,
  					int level,
  					int flags)
  {
  	sprintbuf(pb, "Custom Output");
  	return 0;
  }
  
  int main(int argc, char **argv)
  {
  	json_object *my_object;
  
  	MC_SET_DEBUG(1);
  
  	printf("Test setting, then resetting a custom serializer:\n");
  	my_object = json_object_new_object();
  	json_object_object_add(my_object, "abc", json_object_new_int(12));
  	json_object_object_add(my_object, "foo", json_object_new_string("bar"));
  
  	printf("my_object.to_string(standard)=%s\n", json_object_to_json_string(my_object));
  
  	struct myinfo userdata = { .value = 123 };
  	json_object_set_serializer(my_object, custom_serializer, &userdata, freeit);
  
  	printf("my_object.to_string(custom serializer)=%s\n", json_object_to_json_string(my_object));
  
  	printf("Next line of output should be from the custom freeit function:\n");
  	freeit_was_called = 0;
  	json_object_set_serializer(my_object, NULL, NULL, NULL);
  	assert(freeit_was_called);
  
  	printf("my_object.to_string(standard)=%s\n", json_object_to_json_string(my_object));
  
  	json_object_put(my_object);
  
  	// ============================================
  
  	my_object = json_object_new_object();
  	printf("Check that the custom serializer isn't free'd until the last json_object_put:\n");
  	json_object_set_serializer(my_object, custom_serializer, &userdata, freeit);
  	json_object_get(my_object);
  	json_object_put(my_object);
  	printf("my_object.to_string(custom serializer)=%s\n", json_object_to_json_string(my_object));
  	printf("Next line of output should be from the custom freeit function:\n");
  
  	freeit_was_called = 0;
  	json_object_put(my_object);
  	assert(freeit_was_called);
  
  	return 0;
  }
  