lower the code upkeep for mextra and oextra pointer additions

include/mextra.h

@@ -19,8 +19,8 @@
  *          file.
  *       3. Add a referencing macro at bottom of this file after the mextra
  *          struct (see MNAME, EGD, EPRI, ESHK, EMIN, or EDOG for examples).
- *       4. Zero out the pointer to your struct in newmextra() in
- *          src/makemon.c.
+ *       4. If your new field isn't a pointer and requires a special value
+ *          on initialization, add code to init_mextra() in src/makemon.c
  *       5. Create a newXX(mtmp) function and possibly a free_XX(mtmp)
  *          function in an appropriate new or existing source file and add
  *          a prototype for it to include/extern.h.

include/obj.h

@@ -389,8 +389,8 @@ struct obj {
  *       4. Add a testing macro after the set of referencing macros
  *          (see has_oname(), has_omonst(), has_omailcmd(), and has_omin(),
  *          for examples).
- *       5. Zero out the pointer to your struct in newoextra() in
- *          src/mkobj.c.
+ *       5. If your new field isn't a pointer and requires a special value
+ *          on initialization, add code to init_oextra() in src/mkobj.c.
  *       6. Create newXX(otmp) function and possibly free_XX(otmp) function
  *          in an appropriate new or existing source file and add a prototype
  *          for it to include/extern.h.  The majority of these are currently

src/makemon.c

@@ -1038,19 +1038,23 @@ int mndx;
     }
 }
 
+static const struct mextra zeromextra = { DUMMY };
+
+static void
+init_mextra(mex)
+struct mextra *mex;
+{
+    *mex = zeromextra;
+    mex->mcorpsenm = NON_PM;
+}
+
 struct mextra *
 newmextra()
 {
     struct mextra *mextra;
 
     mextra = (struct mextra *) alloc(sizeof(struct mextra));
-    mextra->mname = 0;
-    mextra->egd = 0;
-    mextra->epri = 0;
-    mextra->eshk = 0;
-    mextra->emin = 0;
-    mextra->edog = 0;
-    mextra->mcorpsenm = NON_PM;
+    init_mextra(mextra);
     return mextra;
 }
 

src/mkobj.c

@@ -67,16 +67,22 @@ static const struct icp hellprobs[] = { { 20, WEAPON_CLASS },
                                         { 8, RING_CLASS },
                                         { 4, AMULET_CLASS } };
 
+static const struct oextra zerooextra = { DUMMY };
+
+static void
+init_oextra(oex)
+struct oextra *oex;
+{
+    *oex = zerooextra;
+}
+
 struct oextra *
 newoextra()
 {
     struct oextra *oextra;
 
     oextra = (struct oextra *) alloc(sizeof (struct oextra));
-    oextra->oname = 0;
-    oextra->omonst = 0;
-    oextra->omailcmd = 0;
-    oextra->omid = 0;
+    init_oextra(oextra);
     return oextra;
 }