blanking novels

Simplify converting novels into blank spellbooks via water damage.
Since that can occur, update cancellation to do it too.

include/extern.h

@@ -3799,6 +3799,7 @@ extern struct monst *revive(struct obj *, boolean) NONNULLARG1;
 extern int unturn_dead(struct monst *) NONNULLARG1;
 extern void unturn_you(void);
 extern void cancel_item(struct obj *) NONNULLARG1;
+extern void blank_novel(struct obj *) NONNULLARG1;
 extern boolean drain_item(struct obj *, boolean) NO_NNARGS; /* tests !obj */
 extern boolean obj_unpolyable(struct obj *) NONNULLARG1;
 extern struct obj *poly_obj(struct obj *, int) NONNULLARG1;

src/trap.c

@@ -4613,16 +4613,8 @@ water_damage(
             obj->spestudied = rn2(obj->spestudied);
         obj->dknown = 0;
         /* blanking a novel is more involved than blanking a spellbook */
-        if (otyp == SPE_NOVEL) { /* old type */
+        if (otyp == SPE_NOVEL) /* old type */
-            obj->novelidx = 0; /* overloads corpsenm, not used for splbooks */
+            blank_novel(obj);
-            free_oname(obj);
-            /* novels weigh less than spellbooks; apparently blanking them
-               magically makes them become heavier */
-            do {
-                obj->owt = weight(obj);
-                obj = (obj->where == OBJ_CONTAINED) ? obj->ocontainer : 0;
-            } while (obj);
-        }
         if (in_invent)
             update_inventory();
         return ER_DAMAGED;

src/zap.c

@@ -1255,9 +1255,11 @@ cancel_item(struct obj *obj)
                          || obj->oclass == WEAPON_CLASS || is_weptool(obj)))
         || otyp == POT_ACID
         || otyp == POT_SICKNESS
-        || (otyp == POT_WATER && (obj->blessed || obj->cursed))) {
+        || (otyp == POT_WATER && (obj->blessed || obj->cursed))
+        /* not magic; cancels to blank spellbook */
+        || otyp == SPE_NOVEL) {
         int cancelled_spe = (obj->oclass == WAND_CLASS
-                             || obj->otyp == CRYSTAL_BALL) ? -1 : 0;
+                             || otyp == CRYSTAL_BALL) ? -1 : 0;
 
         if (obj->spe != cancelled_spe
             && otyp != WAN_CANCELLATION /* can't cancel cancellation */
@@ -1273,10 +1275,12 @@ cancel_item(struct obj *obj)
             obj->spe = 0;
             break;
         case SPBOOK_CLASS:
-            if (otyp != SPE_CANCELLATION && otyp != SPE_NOVEL
+            if (otyp != SPE_CANCELLATION && otyp != SPE_BOOK_OF_THE_DEAD) {
-                && otyp != SPE_BOOK_OF_THE_DEAD) {
                 costly_alteration(obj, COST_CANCEL);
                 obj->otyp = SPE_BLANK_PAPER;
+                /* cancelling a novel is more involved than a spellbook */
+                if (otyp == SPE_NOVEL) /* old type */
+                    blank_novel(obj);
             }
             break;
         case POTION_CLASS:
@@ -1313,6 +1317,20 @@ cancel_item(struct obj *obj)
     return;
 }
 
+/* soaking or cancelling a novel converts it into a blank spellbook but
+   needs more than just changing its otyp (caller is responsible for that) */
+void
+blank_novel(struct obj *obj)
+{
+    assert(obj->otyp == SPE_BLANK_PAPER);
+    /* novelidx overloads corpsenm, not used for spellbooks */
+    obj->novelidx = 0;
+    free_oname(obj); /* get rid of [former] novel's title */
+    /* a blank spellbook weighs more than a novel; update obj's weight and
+       recursively the weight of any container holding it */
+    container_weight(obj);
+}
+
 /* Remove a positive enchantment or charge from obj,
  * possibly carried by you or a monster
  */