clarify use_potion responsibilities.

move USE potion of life to items.c.
fix some use_ function return values.

scripts/eressea/xmasitems.lua

@@ -63,9 +63,10 @@ end
 
 function use_snowman(u, amount)
     if amount > 0 and u.region.terrain == "glacier" then
-        local man = unit.create(u.faction, u.region, amount, "snowman")
+        unit.create(u.faction, u.region, amount, "snowman")
         return amount
     end
+    -- print error76:
     return -4
 end
 
@@ -79,7 +80,8 @@ function use_xmastree(u, amount)
         msg:send_region(u.region)
         return amount
     end
-    return 0
+    -- print error76:
+    return -4
 end
 
 local self = {}

src/alchemy.c

@@ -160,37 +160,6 @@ static void end_potion(unit * u, const item_type * itype, int amount)
         "unit potion", u, itype->rtype));
 }
 
-static int potion_water_of_life(unit * u, region *r, int amount) {
-    static int config;
-    static int tree_type, tree_count;
-    int wood = 0;
-
-    if (config_changed(&config)) {
-        tree_type = config_get_int("rules.magic.wol_type", 1);
-        tree_count = config_get_int("rules.magic.wol_effect", 10);
-    }
-    /* mallorn is required to make mallorn forests, wood for regular ones */
-    if (fval(r, RF_MALLORN)) {
-        wood = use_pooled(u, rt_find("mallorn"), GET_DEFAULT, tree_count * amount);
-    }
-    else {
-        wood = use_pooled(u, rt_find("log"), GET_DEFAULT, tree_count * amount);
-    }
-    if (r->land == 0)
-        wood = 0;
-    if (wood < tree_count * amount) {
-        int x = wood / tree_count;
-        if (wood % tree_count)
-            ++x;
-        if (x < amount)
-            amount = x;
-    }
-    rsettrees(r, tree_type, rtrees(r, tree_type) + wood);
-    ADDMSG(&u->faction->msgs, msg_message("growtree_effect",
-        "mage amount", u, wood));
-    return amount;
-}
-
 void show_potions(faction *f, int sklevel)
 {
     const potion_type *ptype;
@@ -262,11 +231,8 @@ static int potion_healing(struct unit *user, int amount)
 
 static int do_potion(unit * u, region *r, const item_type * itype, int amount)
 {
-    /* TODO: why do some of these take a region argument? */
-    if (itype == oldpotiontype[P_LIFE]) {
-        return potion_water_of_life(u, r, amount);
-    }
-    else if (itype == oldpotiontype[P_PEOPLE]) {
+    /* TODO: this function should only be used for effect-changing potions */
+    if (itype == oldpotiontype[P_PEOPLE]) {
         return potion_luck(u, r, &at_peasantluck, amount);
     }
     else if (itype == oldpotiontype[P_HORSE]) {

src/helpers.c

@@ -249,19 +249,9 @@ lua_changeresource(unit * u, const struct resource_type *rtype, int delta)
 
 /** callback for an item-use function written in lua. */
 static int
-use_item_lua(unit *u, const item_type *itype, int amount, struct order *ord)
+lua_use_item(unit *u, const item_type *itype, const char * fname, int amount, struct order *ord)
 {
     lua_State *L = (lua_State *)global.vm_state;
-    int len, result = 0;
-    char fname[64];
-    int (*callout)(unit *, const item_type *, int, struct order *);
-
-    len = snprintf(fname, sizeof(fname), "use_%s", itype->rtype->_name);
-    if (len > 0 && (size_t)len < sizeof(fname)) {
-    callout = (int(*)(unit *, const item_type *, int, struct order *))get_function(fname);
-    if (callout) {
-        return callout(u, itype, amount, ord);
-    }
 
     lua_getglobal(L, fname);
     if (lua_isfunction(L, -1)) {
@@ -272,23 +262,52 @@ use_item_lua(unit *u, const item_type *itype, int amount, struct order *ord)
         if (lua_pcall(L, 4, 1, 0) != 0) {
             const char *error = lua_tostring(L, -1);
             log_error("use(%s) calling '%s': %s.\n", unitname(u), fname, error);
-            lua_pop(L, 1);
         }
         else {
-            result = (int)lua_tonumber(L, -1);
+            int result = (int)lua_tonumber(L, -1);
             lua_pop(L, 1);
-        }
             return result;
         }
+    }
     lua_pop(L, 1);
+    return 0;
+}
+
+static int
+use_item_callback(unit *u, const item_type *itype, int amount, struct order *ord)
+{
+    int len;
+    char fname[64];
+    int(*callout)(unit *, const item_type *, int, struct order *);
+
+    len = snprintf(fname, sizeof(fname), "use_%s", itype->rtype->_name);
+    if (len > 0 && (size_t)len < sizeof(fname)) {
+        int result;
+
+        /* check if we have a register_item_use function */
+        callout = (int(*)(unit *, const item_type *, int, struct order *))get_function(fname);
+        if (callout) {
+            return callout(u, itype, amount, ord);
+        }
+
+        /* check if we have a matching lua function */
+        result = lua_use_item(u, itype, fname, amount, ord);
+        if (result != 0) {
+            return result;
+        }
+
+        /* if the item is a potion, try use_potion, the generic function for 
+         * potions that add an effect: */
         if (itype->flags & ITF_POTION) {
             return use_potion(u, itype, amount, ord);
-    } else {
+        }
+        else {
             log_error("no such callout: %s", fname);
         }
         log_error("use(%s) calling '%s': not a function.\n", unitname(u), fname);
     }
-    return result;
+
+    return 0;
 }
 
 /* compat code for old data files */
@@ -328,7 +347,7 @@ void register_tolua_helpers(void)
     at_deprecate("lcbuilding", building_action_read);
 
     callbacks.cast_spell = lua_callspell;
-    callbacks.use_item = use_item_lua;
+    callbacks.use_item = use_item_callback;
     callbacks.produce_resource = produce_resource_lua;
     callbacks.limit_resource = limit_resource_lua;
 

src/items.c

@@ -376,10 +376,47 @@ static int use_warmthpotion(unit *u, const item_type *itype,
     return 0;
 }
 
+static int potion_water_of_life(unit * u, region *r, int amount) {
+    static int config;
+    static int tree_type, tree_count;
+    int wood = 0;
+
+    if (config_changed(&config)) {
+        tree_type = config_get_int("rules.magic.wol_type", 1);
+        tree_count = config_get_int("rules.magic.wol_effect", 10);
+    }
+    /* mallorn is required to make mallorn forests, wood for regular ones */
+    if (fval(r, RF_MALLORN)) {
+        wood = use_pooled(u, rt_find("mallorn"), GET_DEFAULT, tree_count * amount);
+    }
+    else {
+        wood = use_pooled(u, rt_find("log"), GET_DEFAULT, tree_count * amount);
+    }
+    if (r->land == 0)
+        wood = 0;
+    if (wood < tree_count * amount) {
+        int x = wood / tree_count;
+        if (wood % tree_count)
+            ++x;
+        if (x < amount)
+            amount = x;
+    }
+    rsettrees(r, tree_type, rtrees(r, tree_type) + wood);
+    ADDMSG(&u->faction->msgs, msg_message("growtree_effect",
+        "mage amount", u, wood));
+    return amount;
+}
+
+static int use_water_of_life(unit *u, const item_type *itype,
+    int amount, struct order *ord)
+{
+    return potion_water_of_life(u, u->region, amount);
+}
+
 void register_itemfunctions(void)
 {
     /* have tests: */
-    /* TODO: potions should really use use_potion */
+    register_item_use(use_water_of_life, "use_p2");
     register_item_use(use_mistletoe, "use_mistletoe");
     register_item_use(use_tacticcrystal, "use_dreameye");
     register_item_use(use_studypotion, "use_studypotion");