8.19. Random choices of things

| Chapter 8: Change |

| 8.19. Random choices of things

Writing "a random number" is not allowed, because the possible range is too large, but that was the only reason why not.

a/-- random (description of values) ... value

This phrase makes a uniformly random choice from values satisfying the description given. Example: a random visited room a random scene A problem message is issued if the range is too large (for instance, "a random text"). Unexpected results may follow if no value fits the description, unless we are describing objects, in which case the result is the special value "nothing".

For instance:

> say "You can see [number of adjacent rooms] way[s] from here; how about [random adjacent room]?"

But it's important to worry about the possibility that nothing qualifies - here, that no adjacent rooms exist. The above would then say:

> You can see 0 ways from here; how about nothing?

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| Example Candy One of several identical candies chosen at the start of play to be poisonous. |
RB

Suppose we want to give the player a bag of candies, of which a random one is poisonous. We can pick which one should be poisoned at the start of play, like this: "Candy" The plural of piece of candy is pieces of candy. A piece of candy is a kind of thing. A piece of candy is always edible. Four pieces of candy are in the Halloween bag. Toxicity is a kind of value. The toxicities are safe and poisonous. A piece of candy has a toxicity. A piece of candy is usually safe. The Porch is a room. The player carries the Halloween bag. After eating a poisonous piece of candy: say "Oh, that didn't taste right at all. Oh well!" When play begins: now a random piece of candy is poisonous. Test me with "eat candy / g / g / g".

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| Example Zork II A "Carousel Room", as in Zork II, where moving in any direction from the room leads (at random) to one of the eight rooms nearby. |
RB

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