2.1. Varying What Is Written

| Chapter 2: Adaptive Prose |

| 2.1. Varying What Is Written

Before getting to actual recipes, many recipe books begin with intimidating lists of high-end kitchen equipment (carbon-steel pans, a high-temperature range, a Provencal shallot-grater, a set of six pomegranate juicers): fortunately, readers who have downloaded Inform already have the complete kitchen used by the authors. But the other traditional preliminaries, about universal skills such as chopping vegetables, boiling water and measuring quantities, do have an equivalent.

For us, the most basic technique of IF is to craft the text so that it smoothly and elegantly adapts to describe the situation, disguising the machine which is never far beneath the surface. This means using text substitutions so that any response likely to be seen more than once or twice will vary.

M. Melmoth's Duel demonstrates three basic techniques: an ever-changing random variation, a random variation changing only after the player has been absent for a while, and a message tweaked to add an extra comment in one special case. (Random choices can be quite specifically constrained, as Ahem shows in passing.) Fifty Ways to Leave Your Larva and Fifty Times Fifty Ways show how a generic message can be given a tweak to make it a better fit for the person it currently talks about. Curare picks out an item carried by the player to work into a message, trying to make an apt rather than random choice. Straw Into Gold demonstrates how to have Inform parrot back the player's choice of name for an object.

Another reason to vary messages is to avoid unnatural phrasing. Odins carefully avoids a giveaway grammatical blunder - the kind only a computer would make. Ballpark turns needlessly precise numbers - another computerish trait - into more idiomatic English. (Likewise Numberless, though it is really an example demonstrating how to split behaviour into many cases.) Prolegomena shows how to use these vaguer quantifiers any time Inform describes a group of objects (as in "You can see 27 paper clips here.").

Blink, a short but demanding example from the extreme end of Writing with Inform, shows how the basic text variation mechanisms of Inform can themselves be extended. Blackout demonstrates text manipulation at a lower level, replacing every letter of a room name with "*" when the player is in darkness.

A few of Inform's included extensions provide extra control over text output, as well: Complex Listing allows us more control over the order and presentation of lists of items, and Plurality provides functions for handling pronouns and objects whose names might be understood as singular or plural.

The extension Case Management used to be used for changing the case of something printed, but it is now included chiefly to support older Inform projects: now the best way to change printed text to upper, lower, sentence, or title casing is to use indexed text, as demonstrated in Rocket Man.

178
| Example M. Melmoth's Duel Three basic ways to inject random or not-so-random variations into text. |
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169
| Example Ahem Writing a phrase, with several variant forms, whose function is to follow a rule several times. |
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71
| Example Fifty Ways to Leave Your Larva Using text substitution to make characters reply differently under the same circumstances. |
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72
| Example Fifty Times Fifty Ways Writing your own rules for how to carry out substitutions. |
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428
| Example Curare A phrase that chooses and names the least-recently selected item from the collection given, allowing the text to cycle semi-randomly through a group of objects. |
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294
| Example Straw Into Gold Creating a Rumpelstiltskin character who is always referred to as "dwarf", "guy", "dude", or "man" -- depending on which the player last used -- until the first time the player refers to him as "Rumpelstiltskin". |
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440
| Example Odins Making [is-are] and [it-they] say tokens that will choose appropriately based on the last object mentioned. |
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60
| Example Ballpark A new "to say" definition which allows the author to say "[a number in round numbers]" and get verbal descriptions like "a couple of" or "a few" as a result. |
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174
| Example Numberless A simple exercise in printing the names of random numbers, comparing the use of "otherwise if...", a switch statement, or a table-based alternative. |
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330
| Example Prolegomena Replacing precise numbers with "some" or other quantifiers when too many objects are clustered together for the player to count at a glance. |
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444
| Example Blink Making a "by atmosphere" token, allowing us to design our own text variations such as "[one of]normal[or]gloomy[or]scary[by atmosphere]". |
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Suppose we are writing a game in which the mood of the piece changes, and we would like to have lots of descriptions that vary according to its current state. We might in that case want to create our own "by atmosphere" token, to control text variations, like this: "Blink" Atmosphere is a kind of value. The atmospheres are normal, melancholy, and creepy. The current atmosphere is an atmosphere that varies. To say by atmosphere -- ending say_one_of with marker I7_SOO_ATM: (- {-close-brace} -). Since we're operating within the untyped Inform 6, we can make use of the fact that kinds of value are (internally) just constants, enumerated in the same order in which they were originally defined. In other words, "normal" at the I6 level translates to 1, "melancholy" to 2, and "creepy" to 3; so we can return the value of the current atmosphere, and thereby select option 1, 2, or 3: Include (- [ I7_SOO_ATM oldval count; if (count < (+ current atmosphere +)) return count; return (+ current atmosphere +); ]; -) And that concludes the hard part. Now to test that it works: The Flat is a room. "A small [one of]but cozy[or]depressing[or]imprisoning[by atmosphere] flat. Outside the window, the sun is [one of][or][or]apparently [by atmosphere]shining and there is a brisk breeze through the leaves of the birch trees. [one of]It would be quite nice weather for a walk[or]The rest of the world apparently has no appreciation of what you suffer[or]It all looks deceptively normal[by atmosphere]." Instead of waiting when the current atmosphere is normal: say "Everything stretches wide and flat for just a moment, as though all the world around you were painted on a thin rubber sheet that is being [italic type]stretched[roman type]. Then it snaps back into place, leaving your ears ringing. But that little glitch was enough to warn you. Someone is tampering with space-time again. Someone very close by."; now the current atmosphere is creepy. Test me with "look / z / look".

408
| Example Blackout Filtering the names of rooms printed while in darkness. |
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401
| Example Rocket Man Using case changes on any text produced by a "to say..." phrase. |
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