8.11. Now...

| Chapter 8: Change |

| 8.11. Now...

"Now" has already appeared several times in this chapter, being used like a Swiss army knife to change values of all kinds:

> now the score is 100;

In fact, "now" is by far the most flexible phrase known to Inform.

now (a condition)

This phrase makes the condition become true. Examples: now the score is 100; now the player is Kevin; now the front door is open; now Mr Darcy is wearing the top hat; now all the doors are open; now all of the things in the sack are in the box; Inform issues a problem message if the condition asks to do the impossible ("now 3 is an even number") or is vague ("now the duck is not in the Lily Pond") or not in the present tense ("now the front door had been open").

We've now seen all three things which can be done with a condition S which describes the world:

> S. - The relation holds at the start of play.
> if S, ...; - Does the relation hold right now?
> now S; - Make the relation hold from now on.

For instance,

> The apple is in the basket.
> if the apple is in the basket, ...;
> now the apple is in the basket;

125
| Example Bee Chambers A maze with directions between rooms randomized at the start of play. |
RB

126
| Example Hatless It's tempting to use "now..." to distribute items randomly at the start of play, but we need to be a little cautious about how we do that. |
RB

Suppose we want a game in which each scenario starts with the characters wearing hats -- randomly passed out. We might be tempted to write our scenario like this: "Hatless" The Costumery is a room. Larry, Curly, and Moe are men in the Costumery. Janine is a woman in the Costumery. Rule for writing a paragraph about a person (called the target) who wears a hat (called attire): say "[The target] is here, looking stylish in [an attire]." Rule for writing a paragraph about a hatless person (called the target): say "[The target] mopes about, hatless." A hat is a kind of thing. A hat is always wearable. Definition: a person is hatless if he does not wear a hat. The indigo bowler, the polka-dotted fedora, the pink beret, and the scarlet cloche are hats. When play begins: now every hat is worn by a random hatless person. And we might hope that this would choose a new hatless person for each hat, but we would be wrong. It will instead choose one hatless person and put all the hats on him -- and everyone else has to go bare-headed. That's clearly no good. Let's try again: "Hatless 2" The Costumery is a room. Larry, Curly, and Moe are men in the Costumery. Janine is a woman in the Costumery. Rule for writing a paragraph about a person (called the target) who wears a hat (called attire): say "[The target] is here, looking stylish in [an attire]." Rule for writing a paragraph about a hatless person (called the target): say "[The target] mopes about, hatless." A hat is a kind of thing. A hat is always wearable. Definition: a person is hatless if he does not wear a hat. The indigo bowler, the polka-dotted fedora, the pink beret, and the scarlet cloche are hats. When play begins: now every hatless person wears a random hat. But this selects one random hat and assigns it to each hatless person in turn -- so it will only wind up being worn by the last of them (since Inform knows that only one person can wear a hat at a time). In this case, we do have to expand out our loop so that the game makes an explicit distribution: "Hatless 3" The Costumery is a room. Larry, Curly, and Moe are men in the Costumery. Janine is a woman in the Costumery. Rule for writing a paragraph about a person (called the target) who wears a hat (called attire): say "[The target] is here, looking stylish in [an attire]." Rule for writing a paragraph about a hatless person (called the target): say "[The target] mopes about, hatless." A hat is a kind of thing. A hat is always wearable. Definition: a person is hatless if he does not wear a hat. The indigo bowler, the polka-dotted fedora, the pink beret, and the scarlet cloche are hats. When play begins: repeat with item running through hats: now the item is worn by a random hatless person. Each time Inform considers the instruction "now the item is worn by a random hatless person", there is one fewer such person to choose from -- so we can guarantee that the hats are distributed one per customer and that all hats are distributed. Hatless 3 is only guaranteed to work because the number of hats is less than or equal to the number of people; otherwise the final use of random will return "nothing" and then a problem message will appear during play.

127
| Example Technological Terror A ray gun which destroys objects, leaving their component parts behind. |
RB

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