#include <stdio.h>
#include <stdlib.h>

struct _rect {
	int  x, y;
	int (**prototype)(struct _rect *);
};
typedef struct _rect Rect;

typedef int (*Rect_method)(Rect *); 	/**< method enumeration */

enum { GET_X, GET_Y, END_OF_NAME_TABLE }; 	/**< name table */

Rect_method *rect_prototype; 	/**< method as an array of prototypes */

/* constructor & destructor */
Rect *rect_new(int x, int y)
{
	Rect *p = (Rect *) malloc(sizeof(Rect));
	p->x = x, p->y = y;
	p->prototype = rect_prototype;
	return p;
}
void rect_delete(Rect *p) { free(p); }

/* methods: getter */
int rect_get_x(Rect *p) { return p->x; }
int rect_get_y(Rect *p) { return p->y; }

/* register prototype */
void rect_init_prototype(void)
{
	rect_prototype = (Rect_method *) malloc((sizeof(Rect_method)) *
	                                        END_OF_NAME_TABLE);
	rect_prototype[GET_X] = rect_get_x;
	rect_prototype[GET_Y] = rect_get_y;
}
/* deregister prototype */
void rect_delete_prototype(void) { free(rect_prototype); }

static void test_suite(void)
{
	Rect *r1 = rect_new(1, 2);
	Rect *r2 = rect_new(3, 4);

	printf("r1 = (%d, %d), r2 = (%d, %d)\n",
			r1->prototype[GET_X](r1), r1->prototype[GET_Y](r1),
			r2->prototype[GET_X](r2), r2->prototype[GET_Y](r2));

	rect_delete(r1);
	rect_delete(r2);
}

int main(void)
{
	rect_init_prototype();
	test_suite();
	rect_delete_prototype();
	return 0;
}