The Dial class is an immediate descendant of the Settable class and the immediate ancestor of the NumberedDial and LabeledDial classes. As such, it is not likely to be used much in game code, since if something is a dial at all, it is likely to be either numbered or labeled if it is to be at all useful, and if one wants something more general that a NumberedDial or a LabeledDial the chances are it'll be a Settable, like the slider we implemented before.
There may be one or two niches Dial can fill in game code, however. The most obvious might be a Dial with case-sensitive labels (since the LabeledDial assumes that its labels are not case sensitive). Although there may not be much call for case-sensitive labels, it could be possible to construct a minor puzzle of sorts out of a Dial with such labels, and it's probably easier (or at least, no harder) to do so starting from the Dial class than the LabeledDial class. Basically, all one need do to make it work is to define one's own validSettings list and override the isValidSettings method on such a dial thus:
isValidSetting(val) { return validSettings.indexOf(val) != nil; }
To show how this might work in practice, we'll add one of these in the secret chamber behind the stone altar, which we'll transmogrify into a lift in the process. The dial will be the lift control, which can be turned to thinly-disguised versions of the words UP and DOWN; no other setting has any effect. If the handle is turned to DOWN (disguised as Dupe OWN) the lift descends (unless it's already at the bottom). If it's turned to UP (disguised as dUPe own) the lift ascends again (unless it's already at the top):
templeChamber : DarkRoom 'Small Square Chamber' 'the small square chamber'
"The most noticeable feature of this otherwise featureless chamber is the
way out to the east, "
out = temple
east = (out)
moveInto(newDest)
{
if(out == newDest)
"and nothing happens. ";
else
"and with a shudder, the small chamber <<newDest==temple ? 'ascends' :
'descends'>> a long shaft, and finally comes to a halt. ";
out = newDest;
}
;
+ Dial, Fixture 'curious (wall) dial/handle' 'dial'
"The dial comprises a handle set into the stone work that can be turned to
point to any of the eight phrases carved round its circumference: <<listSettings>>.
It currently points to <i><<curSetting>></i>. "
inRoomDesc = "but there is also a curious dial set into one wall. "
disambigName = 'curious wall dial'
curSetting = 'DUPE OWN'
listSettings()
{
stringLister.showSimpleList(validSettings);
}
validSettings = ['dupe own', 'dupE own', 'dUPe own', 'DUPe own',
'Dupe OWN', 'DUPE oWn', 'DUPE oWN', 'DUPE OWN']
isValidSetting(val) { return validSettings.indexOf(val) != nil; }
makeSetting(val)
{
if(val == curSetting)
{
"The dial already points to <i><<val>></i>. ";
return;
}
"You turn the dial to <i><<val>></i>, ";
switch(val)
{
case 'dUPe own': templeChamber.moveInto(temple); break;
case 'Dupe OWN': templeChamber.moveInto(templeCellar); break;
default: "but nothing happens. ";
}
inherited(val);
}
;
Note that we have to change the definition of templeChamber.east, since the asExit macro won't do what we want if it refers to a directional property we subsequently change. Note also that we have overridden templeChamber.moveInto to something quite different from what moveInto normally does; we could have used any method name we liked for this, but moveInto is quite descriptive here, and we have no use for the standard Thing.moveInto handling here, so we might as well replace it. Finally, note that we define a listSettings method to avoid (the tedious and possibly error-prone process of) writing out the possible settings of the dial twice. This calls the convenient stringLister.showSimpleList() method to format the list in the form "a, b, c and d".
Finally, we need to define the location the list/chamber arrives at if the dial is turned to the Dupe OWN position. As an attempt at brevity we might write:
templeCellar : DarkRoom 'Cellar beneath Temple' 'the cellar beneath the Temple'
"This long, damp cellar probably hasn't been visited in years. "
lift = templeChamber
west = (lift.out == self ? lift : nil)
;
The west property shows a possible but not very sanitary method of checking that the lift is in place before allowing entry to it. It works after a fashion, but will cause an immediate runtime error if you then added, for example:
in asExit(west)
Although we probably won't be implementing any other way into the temple cellar than via the lift, so the lift will always be available to the west when the player character is in the cellar, if we want to make this kind of test at all, it would be far better to use the recommended method we have already seen (using a nested TravelConnector), even though it is a bit more long-winded:
templeCellar : DarkRoom 'Cellar beneath Temple' 'the cellar beneath the Temple'
"This long, damp cellar probably hasn't been visited in years. "
lift = templeChamber
west: OneWayRoomConnector
{
destination = (lexicalParent.lift)
canTravelerPass(traveler)
{
return lexicalParent.lift.out == lexicalParent;
}
explainTravelBarrier(traveler)
{
"There's nothing that way but an empty shaft. ";
}
}
;
The above definition could be made a bit less verbose if we dispensed with the lift property and replaced each instance of lexicalParent.lift with templeChamber.