refactor stray fptr variable into callbacks module.

src/helpers.c

@@ -310,11 +310,10 @@ void register_tolua_helpers(void)
     at_register(&at_building_action);
 
     callbacks.cast_spell = lua_callspell;
-
+    callbacks.use_item = use_item_lua;
-    register_function((pf_generic)lua_changeresource, "lua_changeresource");
-
-    item_use_fun = use_item_lua;
     res_produce_fun = produce_resource_lua;
     res_limit_fun = limit_resource_lua;
+
+    register_function((pf_generic)lua_changeresource, "lua_changeresource");
     register_item_give(lua_giveitem, "lua_giveitem");
 }

src/kernel/callbacks.h

@@ -24,9 +24,15 @@ extern "C" {
 #endif
 
     struct castorder;
+    struct order;
+    struct unit;
+    struct item_type;
 
     struct callback_struct {
         int (*cast_spell)(struct castorder *co, const char *fname);
+        int (*use_item)(struct unit *u, const struct item_type *itype,
+            int amount, struct order *ord);
+
     };
 
     extern struct callback_struct callbacks;

src/kernel/resources.c

@@ -213,8 +213,6 @@ struct rawmaterial_type *rmt_create(struct resource_type *rtype)
     return rmtype;
 }
 
-int(*item_use_fun)(struct unit *u, const struct item_type *itype, int amount,
-    struct order *ord);
 int(*res_limit_fun)(const struct region *, const struct resource_type *);
 void(*res_produce_fun)(struct region *, const struct resource_type *, int);
 

src/kernel/resources.h

@@ -73,8 +73,6 @@ extern "C" {
 
     extern int(*res_limit_fun)(const struct region *, const struct resource_type *);
     extern void(*res_produce_fun)(struct region *, const struct resource_type *, int);
-    extern int (*item_use_fun)(struct unit *, const struct item_type *, int amount,
-        struct order *ord);
     int limit_resource(const struct region *r, const struct resource_type *rtype);
     void produce_resource(struct region *r, const struct resource_type *rtype, int amount);
 

src/laws.c

@@ -45,6 +45,7 @@ OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 /* kernel includes */
 #include <kernel/alliance.h>
 #include <kernel/ally.h>
+#include <kernel/callbacks.h>
 #include <kernel/connection.h>
 #include <kernel/curse.h>
 #include <kernel/building.h>
@@ -3218,7 +3219,7 @@ static int use_item(unit * u, const item_type * itype, int amount, struct order
     }
 
     if (itype->flags & ITF_CANUSE) {
-        int result = item_use_fun(u, itype, amount, ord);
+        int result = callbacks.use_item(u, itype, amount, ord);
         if (result > 0) {
             use_pooled(u, itype->rtype, GET_DEFAULT, result);
         }