Adding first version of object.c for ch20 ex19

object.c

@@ -0,0 +1,73 @@
+#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->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(size, 1);
+    *el = proto;
+
+    // copy the description over
+    el->description = strdup(description);
+
+    // initialize it with whatever init we were given
+    if(!el->init(el)) {
+        // looks like it didn't initialize properly
+        el->destroy(el);
+        return NULL;
+    } else {
+        // all done, we made an object of any type
+        return el;
+    }
+}