How to Deal with Some Common Problems with Phantasmal's APIs

Q: I try adding my own custom room (or portable), using custom lpc code, but
when I start the MUD I get the following messages:

Sep  3 20:12:16 ** DGD 1.2.47
Sep  3 20:12:16 ** Initializing...
You forgot to register with MAPD in a room object def maybe?
Config error: initialization failed

The log gives something like this:

-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-
Starting MUD...
-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-
/usr/System/sys/errord(unset) ||| Tue Sep  3 20:12:27 2002 / 0.274 [6]
  --> Runtime error: You forgot to register with MAPD in a room object def maybe?
 441 initialize        /kernel/sys/driver
 429 _initialize       /kernel/sys/driver
 131 create            /usr/System/initd
 433 add_unq_text_rooms /usr/common/sys/mapd
 402 add_dtd_unq_rooms /usr/common/sys/mapd
 342 add_struct_for_room /usr/common/sys/mapd

What's wrong?

A:  You've probably forgotten to register the room with MAPD in the create()
function of your custom room.  Just something like the following in
the create() function of your custom room:

if (clone) {
  ...

  MAPD->add_room_object(this_object());
}

(Contributed by Keith Dunwoody <keithdunwoody@yahoo.com>)