#ifndef _DOG_H_
#define _DOG_H_

typedef struct dog_st *Dog;

// all dogs know how to delete themselves, bark, and
// encode themselves as a string
struct dog_vtable_st {
  void (*delete)(Dog d);
  void (*bark)(Dog d);
  char *(*toString)(Dog d);
};

typedef struct dog_st {
  struct dog_vtable_st *vtable;
  char *name;
  int age;
} *Dog;

// separate allocation of dog from initialization
Dog new_dog(char *name, int age);
int _dog_constructor(Dog d, char *name, int age);

void _delete(Dog d);
void _bark(Dog d);

#endif //_DOG_H_