4.12. Values that vary

Sometimes a value important to the simulated world will not naturally belong to any thing or room, and should not be kept in a property. In fact, we have seen a value that varies already: "location", which holds the room in which the story is presently taking place. Here's how we might make a new one:

Or "which varies" would also be allowed, as would the more traditional computing term "variable":

A briefer way to do this is to use the word "initially", which alerts Inform to the possibility that the value will change in future:

It's not compulsory to give an initial value. If we do not, Inform will use the default value for its kind. (See the table in the Kinds index.) For example, writing just

We can have variables of any of the kinds of value, including new ones, but should watch out for a potential error. If we write:

in a world which has no containers at all, Inform will object, because it will be unable to put any initial value into the receptacle variable. A similar complaint will be made if we write:

without ever having defined any colours. Something else we are not permitted is:

because the openness of a given container may change during play, so that the value in the variable might suddenly become invalid even though the variable itself had not changed.

it has to make a decision about the kind of "accursed one". Peter is a "man", so that seems like the right answer, but Inform wants to play safe in case the variable later needs to change to a woman called Jane, say, or even a black hat. So Inform in fact creates "accursed one" as an object that varies, not a man that varies, to give us the maximum freedom to use it. If we don't want that then we can override it:

ExampleReal Adventurers Need No Help
Allowing the player to turn off all access to hints for the duration of a game, in order to avoid the temptation to rely on them overmuch.

Suppose we have an action called "asking for help" that gives the player some hints on request. We've also made it possible to turn this feature off, if the player would like to discourage himself from using the hints too much. Now we need a value that varies to keep track of whether hints are currently permitted or currently not permitted. So we might write:

"Real Adventurers Need No Help"

A permission is a kind of value. The permissions are allowed and denied.

Hint usage is a permission that varies. Hint usage is allowed.

And under the right circumstances, we change hint usage to denied:

Check asking for help for the first time:
    say "Sometimes the temptation to rely on hints becomes overwhelming, and you may prefer to turn off hints now. If you do so, your further requests for guidance will be unavailing. Turn off hints? >";
    if player consents:
        now hint usage is denied;
        say "[line break]Truly, a real adventurer does not need hints." instead.

Then we can refer back to this value later to decide whether we want to display the hint menu or not:

Check asking for help:
if hint usage is denied, say "You have chosen to eschew hints in this game. Be strong! Persevere!" instead.

Asking for help is an action out of world. Understand "help" or "hint" or "hints" as asking for help.

The Realm of Terribly Unjust Puzzles is a room.

Carry out asking for help:
say "Fine, since you're weak enough to ask: here is a complete walkthrough: GET EGG. PEEL EGG. SMELL EGG. DIVIDE YOLK INTO THREE PORTIONS. GIVE THE SMALLEST PORTION OF YOLK TO THE GOLDEN GOOSE. ASK THE GOOSE ABOUT WHETHER THE SWAN IS TO BE TRUSTED. GIVE THE LARGEST PORTION OF YOLK TO THE SWAN. DANCE CONGA. EAT MEDIUM PORTION. STAND ON HEAD. WEST."

Test me with "hint".

Note that it would probably be kinder to offer the player some intermediate level of help, in the actual event.

	Start of Chapter 4: Kinds
	Back to §4.11. Default values of kinds
	Onward to §4.13. Values that never vary