valid_override - controls the use of efun:: 

int valid_override( string file, string efun_name, string mainfile );

File will be the actual file the call appears in; mainfile will be the file
being compiled (the two can differ due to #include)

Add valid_override to master.c in order to control the use of the efun::
prefix.  The valid_override function in master.c will be called each
time the driver attempts to compile a function call that begins with
efun::.  If valid_override returns 0, then that compile will fail.  Thus
valid_override provides a way to modify the behavior of efuns that isn't
circumventable via the efun:: prefix (by having a simul_efun of the same
name as the efun to be modified and having valid_override disallow that
simul_efun from being overriden).

If you wish to have the original 3.1.2 efun:: behavior, simply add
a line to master.c that looks like this:

<pre>
   int valid_override(string file, string efun) { return 1; }
</pre>

Here is an example valid_override that is more restrictive:
<pre>
  int
  valid_override(string file, string name)
  {
      if (file == "/adm/obj/simul_efun") {
          return 1;
      }
      if (name == "destruct")
          return 0;
      if (name == "shutdown")
          return 0;
      if (name == "snoop")
          return 0;
      if (name == "exec")
          return 0;
      return 1;
   }
</pre>

See also:
 valid_object,
 function_exists

 Tim Hollebeek  Beek@ZorkMUD, Lima Bean, IdeaExchange, and elsewhere