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Moonmist
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META-LOC unreliable when called during DESCRIBE-OBJECTS, e.g. Bolitho doesn't always take your luggage #39

Open eriktorbjorn opened 3 years ago

eriktorbjorn commented 3 years ago

It's possible to get to your bedroom without encountering Bolitho. That gives you much more freedom to either wait for him or walk in on him. If you are carrying your luggage, he's supposed to take it for you. But that doesn't always happen. If he walks in on you:

>WAIT
[I assume you mean: Wait 10 minutes.]
Time passes...
An elderly butler appears. He bows slightly to you. He takes your luggage. "I'll
carry your luggage to your bedroom."

But if you walk in on him:

>DOWN
You go quickly toward the kitchen.
(You are now in the kitchen.)
The kitchen is large yet cramped. From here, you can go west to the tower
basement, east to the servants' quarters, or up the stairs.
An elderly butler appears. He bows slightly to you.
An appetizing aroma wafts from an array of covered dishes sitting about.

You see a brass lantern here.
Bolitho coughs diffidently and asks, "Sneaky? Am I right in assuming that you
are the well-known young American detective?"

This is because the interaction is, somewhat surprisingly, handled by Bolitho's description routine, BUTLER-D:

          (<AND <NOT <EQUAL? <SET L <META-LOC ,LUGGAGE>>
                 ,YOUR-ROOM ,YOUR-BATHROOM>>
            <T? <GETP .L ,P?LINE>>>
           <COND (<IN? ,LUGGAGE ,BUTLER>
              <TELL " He has " D ,LUGGAGE ".">)
             (<==? <LOC ,BUTLER> .L>
              <PUT .GT ,GOAL-FUNCTION ,BUTLER-CARRIES>
              <ESTABLISH-GOAL ,BUTLER ,YOUR-ROOM>
              <FCLEAR ,LUGGAGE ,OPENBIT>
              <MOVE ,LUGGAGE ,BUTLER>
              <TELL " He takes " D ,LUGGAGE ".">)

The description routine is called Also surprisingly, the description routine is called from DESCRIBE-OBJECTS, as you might expect, but also when an NPC enters a room. See MOVE-PERSON and GOAL-REACHED. That's why you get the message when Bolitho enters the room, I think.

But when the room is described, the player gets moved out of the room and into PSEUDO-OBJECT. See DESCRIBE-OBJECTS:

      ;"Hide invisible objects"
    <SET OBJ <FIRST? .THING>>
    <COND (<ZERO? .OBJ>
           <RFALSE>)>
    <REPEAT ()
        <COND (.OBJ
               <SET NXT <NEXT? .OBJ>>
               <COND (<OR <FSET? .OBJ ,INVISIBLE>
                  <FSET? .OBJ ,NDESCBIT>
                  <EQUAL? .OBJ ,WINNER>
                  <AND <FSET? .OBJ ,PERSONBIT>
                       <OR <FSET? .OBJ ,RMUNGBIT>;"not desc'd"
                       ;<IN-MOTION? .OBJ>>>
                  <EQUAL? .OBJ <LOC ,PLAYER>>>
                  <FCLEAR .OBJ ,RMUNGBIT>
                  <MOVE .OBJ ,PSEUDO-OBJECT>)>
               <SET OBJ .NXT>)
              (T
               <RETURN>)>>

These objects aren't moved back to the room until the very end of DESCRIBE-OBJECTS. The result is that META-LOC cannot be trusted while the room is being described, e.g. not in any description routine.

For reference, this is how I avoided Bolitho at the start of the game:

>HONK HORN
>SNEAKY MCSNEAK
>YES
>RED
>YES
>TAKE LUGGAGE
>SOUTH
>YES
>SOUTH
>SOUTH
>UP
>NO
>NO
>UP
>EAST