3.27. Review of Chapter 3: Things

| Chapter 3: Things |

| 3.27. Review of Chapter 3: Things

1. Inform turns our description of the initial situation into a model world, in which the places and items important to the story are objects. These objects come in different kinds. In the course of Chapter 3, we have seen all of the kinds of object built into Inform. If we turn to the Kinds tab in the Index of any project, we can see these kinds set out:

> room
> thing
> door
> container
> player's holdall
> vehicle
> supporter
> backdrop
> person
> animal
> man
> woman
> device
> direction
> region

2. Inform automatically creates a person, called "yourself", and some directions - north, east, south, and so on - but nothing more. We are allowed to create instances of any kind, including more people and further directions (though directions have to be created in opposite pairs). The only absolute requirement is that we must create at least one room, so that the player can begin somewhere.

Sometimes we explicitly declare the kind of something, as here:

> In the Counting House is a device called the clockwork register.

But Inform also deduces kinds from context. For instance, from

> The Royal Treasury is north of the Counting House.
> The glass vase is on the mantelpiece.

Inform deduces that the Treasury and Counting House have kind "room", and that the mantelpiece is a "supporter".

3. All these objects are related in order to make up the model world.

The map lays out the rooms with connections between them, each in its own direction. A map connection either connects two rooms, or one room and one door. Inform assumes that map connections are two-way unless told otherwise. We can see the map for a project using the World index.

A door is normally present in two rooms at once, and connected to each as part of the map:

> The red door is north of the Counting House and south of the Treasury.

A backdrop is a piece of scenery which can be touched by the player, but not picked up or moved, and which is present in several rooms at once. Except for doors and backdrops, a thing can only be in one room at a time.

Things can then be in rooms or containers; on supporters; part of other things; or carried by or worn by people. (We shall see how to create new relations in the chapter on Relations: this will allow us to make much more subtle, or conceptually different, model worlds.)

4. The Kinds index tells us that things are

> Normally unlit not lit, inedible not edible, opaque not transparent, described not undescribed, portable not fixed in place, unmarked for listing not marked for listing.

Lit things give light to their surroundings; unlit things do not. Edible things can be eaten by the player, and when this happens they vanish from the game world. Transparent things - usually containers - reveal their contents even when closed, and allow light to pass through. Portable things can be carried. (The "described" and "marked for listing" properties are not relevant for setting up the world, but are instead used in play to organise room descriptions: see the chapter on Activities.)

The Kinds index continues with the information that things are

> Not normally enterable, scenery, wearable, handled, pushable between rooms, mentioned.

Enterable things respond to ENTER or SIT ON, and are usually either containers or supporters. Scenery cannot be picked up, and is not included in the

> You can see...

paragraph which sometimes concludes a room description: it is best used for items which are named in the room's description. Wearable things are those which can be worn by people: Inform assumes that anything worn at the start of play is wearable. Things pushable between rooms respond to such commands as PUSH CART WEST. ("Handled" and "mentioned" are, again, to do with behaviour in play: something is handled once it has been taken for the first time; "mentioned" is used in constructing room descriptions.)

5. Moving on to properties with values, a thing

> Can have description, printed name, initial appearance, printed plural name, indefinite article.

The description is what we see after "LOOK AT THING", and the initial appearance, if provided, is a paragraph about the object that will appear in the room description where the object is (provided it has never been taken - hence "initial"). The printed name is the name used in all sentences such as

> You can see a dog here...

and the printed plural name is used when the item is one of several of the same kind, as in

> You can see seven dogs here.

It is usually not necessary to set these by hand, though occasionally if we have items oddly named it is worth doing so. (We can also override these entirely with more complicated instructions using the "printing the name..." and "printing the plural name..." activities described later.)

Likewise Inform will do its best to assign a sensible indefinite article ("a" or "some" by default), but we can override its opinions and set this ourselves, for items such as "your mother". Calling an object "Some bread..." or similar at the first mention will establish that that object is to be considered as grammatically plural. Saying something like "a thing called the door" will indicate that the door should always be called "the" and never "a"; and leaving off the article entirely will prevent one from being printed afterward, as Inform decides that the object has a proper name like Matilda or Jerome.

6. Other kinds have additional properties: containers and doors can be open or closed, locked or unlocked, lockable or not lockable, all of which have the meanings we might expect. We may give something its own key by saying, for instance,

> The blue key unlocks the grey door.

Devices may be switched on or switched off, though we will have to add our own instructions about what they do when these conditions pertain.

Containers, supporters, and people may be assigned a carrying capacity, determining how many things they are allowed to contain, support, or possess; things worn are not counted towards the carrying capacity of a person.

7. Rooms may be lighted or dark, visited or unvisited. The former we may set ourselves at the outset of play, and it will not change unless we say so. (Whether there is actually darkness in a "dark" room depends on the circumstances: a player who takes a lit candle into the room will be able to see.)

The visited property is used by Inform to keep track of whether or not the player has been to any given room, or - to be more specific - whether the player has ever completed a LOOK action in that room. Therefore, if we ask

> if the Lawn Furniture Sales Department is visited...

the answer will be "no" up to and during the first printing of the room's description, and "yes" forever thereafter.

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