object.c

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include "object.h"
#include <assert.h>

void Object_destroy(void *self)
{
	Object *obj = self;

	if(obj) {
		if (obj->description)
		  free(obj);
	}
} 

void Object_describe(void *self)
{
	Object *obj = self;
	printf("%s.\n", obj->description);
}

int Object_init(void *self) {
	// do nothing really
	return 1;
}

void *Object_move(void *self, Direction direction) 
{	
	printf("You can't go that direction.\n");
	return NULL;
}

int Object_attack(void *self, int damage)
{
	printf("You can't attack that.\n");
	return 0;
}

void *Object_new(size_t size, Object proto, char *description)
{
	// setup the default functions in case they aren't set
	if (!proto.init) 
	  proto.init = Object_init;
	if (!proto.describe) 
	  proto.describe = Object_describe;
	if (!proto.destroy) 
	  proto.destroy = Object_destroy;	
	if (!proto.attack) 
	  proto.attack = Object_attack;
	if (!proto.move) 
	  proto.move = Object_move;

	// this seems weird, but we can make a struct of one size,
	// then point a different pointer at it to "cast" it
	Object *el = calloc(1, size);
	*el = proto;

	// copy the description over
	el->description = strdup(description);

	// initialize it with whatever init we were given
	if (!el->init(el)) {
	  // looks lie it didn't initialize properly
	  el->destroy(el);
	  return NULL;
	}
	else {
	  // all done we made an object of any type
	  return el;
	}
}