#ifndef _CIRCLE_H_ #define _CIRCLE_H_ #include "common.h" #include "shape.h" struct _circle { int invalid; // super struct _shape *shape; // attribute double radius; // method // void (*area)(void *self); // void (*draw)(void *self); }; struct _circle *circle_new(double radius); double circle_area(void *self, void *parent); void circle_draw(void *self, void *parent); #endif