Night Sky
Example 147
★Sometimes a nice effect is to change the way things are described depending on the information the player has gained in the course of play. We could for instance write this:
"Night Sky"
The Planetarium is a room. "[if we have examined the sinister message]A dark room where it seems something is about to jump out at you![otherwise]A tranquil dark room with a ceilingful of stars.[end if]"
The sinister message is a thing in the Planetarium. "A message is taped to the wall." The description is "'BEWARE.'"
Test me with "look / x message / look".
Test me with "look / x message / look".
Planetarium
A tranquil dark room with a ceilingful of stars.
A message is taped to the wall.
>(Testing.)
>[1] look
Planetarium
A tranquil dark room with a ceilingful of stars.
A message is taped to the wall.
>[2] x message
"BEWARE."
>[3] look
Planetarium
A dark room where it seems something is about to jump out at you!
A message is taped to the wall.
A tranquil dark room with a ceilingful of stars.
A message is taped to the wall.
>(Testing.)
>[1] look
Planetarium
A tranquil dark room with a ceilingful of stars.
A message is taped to the wall.
>[2] x message
"BEWARE."
>[3] look
Planetarium
A dark room where it seems something is about to jump out at you!
A message is taped to the wall.
On the other hand, beware that this would not work as desired:
"Night Sky"
The Planetarium is a room. "[if we have listened to the sinister message]A dark room where it seems something is about to jump out at you![otherwise]A tranquil dark room with a ceilingful of stars.[end if]"
The sinister message is a thing in the Planetarium. "A message plays very softly, so that you would have to listen to hear it." Instead of doing anything other than listening to the message: say "It's only a sound, after all.". Instead of listening to the sinister message: say "A voice whispers, 'BEWARE'."
Test me with "listen to message / look".
Test me with "listen to message / look".
Planetarium
A tranquil dark room with a ceilingful of stars.
A message plays very softly, so that you would have to listen to hear it.
>(Testing.)
>[1] listen to message
A voice whispers, "BEWARE".
>[2] look
Planetarium
A tranquil dark room with a ceilingful of stars.
A message plays very softly, so that you would have to listen to hear it.
A tranquil dark room with a ceilingful of stars.
A message plays very softly, so that you would have to listen to hear it.
>(Testing.)
>[1] listen to message
A voice whispers, "BEWARE".
>[2] look
Planetarium
A tranquil dark room with a ceilingful of stars.
A message plays very softly, so that you would have to listen to hear it.
The reason is that our Instead rule has pre-empted normal listening, so Inform considers that we have never successfully heard the message. The moral here is that "if we have…" is useful for tracking events that otherwise proceeded completely normally (picking up ordinary objects, examining things); if we have used instead to make some change, we will have to use a different approach to record that the event did occur as scheduled.