| Chapter 6: Descriptions |

| 6.6. To be able to see and touch

Two of the adjectives built into Inform are:

> "visible" - the player can see this
> "touchable" - the player can touch this

So we can write descriptions such as "someone visible" or "a touchable container". We also have adjectives "invisible" and "untouchable", as might be expected. The visibility adjectives are particularly useful because the following is likely to go wrong:

> if Helen is in a dark room, ...

This tests whether the room is dark, of itself; Helen may in fact be able to see by means of a torch, but the room is still "dark".

We can also talk about what other people can see and touch:

> something able to be seen by Helen
> something which can be seen by Helen

are synonymous. Similarly for touch; and we can write such conditions as

> if Helen is unable to see Agamemnon, ...
> if Cressida can see Troilus, ...

Note that it is essential to establish who does the seeing and touching: so "something which can be seen" will not be allowed, whereas "something which can be seen by Helen" will.

In fact, inside Inform the adjective "invisible" (for instance) has the following straightforward definition:

> Definition: Something is invisible if the player cannot see it.

The exact definitions of visibility and touchability are complicated, because there are so many ways in which vision and touch can be obstructed, but the gist is that they behave as one would expect. Note that in darkness, nothing is visible, and that nobody can see from one room to another. In general anything invisible is also untouchable, but there are a few exceptions to do with being in the dark. Lastly, the player's own body (the player-character object, which is called "yourself" during play) is both visible (in light) and touchable.

| One day "something which Helen can see" will be allowed, I hope, but for the moment "who" and "which" must be directly followed by the verb.

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| Example Lean and Hungry A thief who will identify and take any valuable thing lying around that he is able to touch.

"Lean and Hungry" Substance is a kind of value. The substances are silver, gold, and lead. Everything has a substance. A thing is usually lead. Definition: a thing is valuable if it is not lead. The Limestone Cave is a room. "Not very big, and it doesn't go back far, but you'd hoped to find some shelter here. Outside it is raining exceptionally hard." The sinister gentleman is a man in the Cave. "Leaning against the wall is a sinister gentleman in a threadbare waistcoat." The description is "He looks as though he might once have been quite well off." After examining the gentleman: say "[The noun] smiles back at you in an unnerving fashion." Now we make the rule that governs the gentleman's behavior. Here we're going to invoke the rules that allow characters besides the player to do actions. More about this can be found in the Advanced Actions chapter: Every turn: if the sinister gentleman can touch something valuable (called the treasure) which is not carried by a person begin; try the gentleman trying taking the treasure; end if. Report the gentleman trying taking something: say "[The gentleman] slyly acquires [the noun] and tucks it into his pocket." instead. That "not carried by a person" prevents the gentleman from stealing from the player (or, less plausibly, from himself). If we did want him to pick pockets, we could just have said "which is not carried by the gentleman". The player is carrying a coin, a bust of Abraham Lincoln, a bottle of sherry, a small pistol, and a wad of Confederate cash. The coin is gold. The pistol is silver. A locket is in the Cave. The locket is gold. "A broken gold locket lies on the ground, a token of your late Mama." Test me with "get locket / i / drop locket / z / drop cash / z / x gentleman / drop all / z / z / look".

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