The following table lists every library-defined property.
The banner headings give the name, what type of value makes sense and
the default value (if other than 0). The symbol (+) means “this
property is additive” so that inherited values from class
definitions pile up into a list, rather than wipe each other out.
Recall that false is the value 0 and true
the value 1.
n_to, s_to, e_to, w_to, ... |
Room, object or routine |
For rooms These twelve
properties (there are also ne_to, nw_to,
se_to, sw_to, in_to,
out_to, u_to and d_to) are
the map connections for the room. A value of 0 means “can't
go this way”. Otherwise, the value should either be a room
or a door object: thus, e_to might be set
to crystal_bridge if the direction “east”
means “over the crystal bridge”.
Routine returns The room or object the map connects
to; or 0 for “can't go this way”; or 1 for “can't
go this way; stop and print nothing further”.
Warning Do not confuse the direction properties
n_to and so on with the twelve direction objects,
n_obj et al.
add_to_scope |
List of objects or routine |
For objects
When this object is in scope (unless it was itself only placed in scope
by PlaceInScope) so are all those listed, or all those
nominated by the routine. A routine given here should call
PlaceInScope(obj) to put obj in scope.
No return value
after |
Routine NULL (+) |
Receives actions after they have happened, but before
the player has been told of them.
For rooms All actions taking place in
this room.
For objects All actions for which this
object is noun (the first object specified in the
command); and all fake actions for it.
Routine returns false
to continue (and tell the player what has happened), true to
stop here (printing nothing).
The Search action is a slightly special
case. Here, after is called when it is clear that it
would be sensible to look inside the object (e.g., it's an open container
in a light room) but before the contents are described.
article |
String or routine "a" |
For objects Indefinite article for
object or routine to print one.
No return value
articles |
Array of strings |
For objects If given, these are the articles used with the object's name. (Provided for non-English languages where irregular nouns may have unusual vowel-contraction rules with articles: e.g., with French non-mute ‘H’.)
before |
Routine NULL (+) |
Receives advance warning of actions (or fake actions)
about to happen.
For rooms All actions taking place in
this room.
For objects All actions for which this
object is noun (the first object specified in the command);
and all fake actions, such as Receive and LetGo
if this object is the container or supporter concerned.
Routine returns false to
continue with the action, true to stop here (printing nothing).
First special case: A vehicle object receives the
Go action if the player is trying to drive around in it.
In this case:
Routine returns 0 to disallow as usual;
1 to allow as usual, moving vehicle and player; 2 to disallow but do
(and print) nothing; 3 to allow but do (and print) nothing. If you
want to move the vehicle in your own code, return 3, not 2: otherwise
the old location may be restored by subsequent workings.
Second special case: in a PushDir
action, the before routine must call AllowPushDir()
and then return true in order to allow the attempt (to
push an object from one room to another) to succeed.
cant_go |
String or routine "You
can't go that way." |
For rooms Message, or routine to print
one, when a player tries to go in an impossible direction from this
room.
No return value
capacity |
Number or routine 100 |
For objects Number of objects a
container or supporter can hold.
For the player-object Number of things
the player can carry (when the player is this object); the default
player object (selfobj) has capacity initially
set to the constant MAX_CARRIED.
daemon |
Routine |
This routine is run each turn, once it has been
activated by a call to StartDaemon, and until stopped
by a call to StopDaemon.
describe |
Routine NULL (+) |
For objects Called when the object is
to be described in a room description, before any paragraph break
(i.e., skipped line) has been printed. A sometimes useful trick is
to print nothing in this routine and return true, which
makes an object ‘invisible’.
For rooms Called before a room's long
(“look”) description is printed.
Routine returns false to
describe in the usual way, true to stop printing here.
description |
String or routine |
For objects The Examine
message, or a routine to print one out.
For rooms The long (“look”)
description, or a routine to print one out.
No return value
door_dir |
Direction property or routine |
For compass objects When the player
tries to go in this direction, e.g., by typing the name of this object,
then the map connection tried is the value of this direction property
for the current room. For example, the n_obj “north”
object normally has door_dir set to n_to.
For objects The direction that this
door object goes via (for instance, a bridge might run
east, in which case this would be set to e_to).
Routine returns The direction property to try.
door_to |
Room or routine |
For objects The place this door object
leads to. A value of 0 means “leads nowhere”.
Routine returns The room. Again, 0 (or
false) means “leads nowhere”. Further, 1
(or true) means “stop the movement action immediately
and print nothing further”.
each_turn |
String or routine NULL (+) |
String to print, or routine to run, at the end of
each turn in which the object is in scope (after all timers and daemons
for that turn have been run).
No return value
found_in |
List of rooms or routine |
This object will be found in all of the listed rooms,
or if the routine says so, unless it has the attribute absent.
If an object in the list is not a room, it means “present in
the same room as this object”.
Routine returns true to be
present, otherwise false. The routine can look at the current
location in order to decide.
Warning This property is only looked at
when the player changes rooms.
grammar |
Routine |
For animate or
talkable objects This is called when the parser
has worked out that the object in question is being spoken to, and
has decided the verb_word and verb_wordnum
(the position of the verb word in the word stream) but hasn't yet tried
any grammar. The routine can, if it wishes, parse past some words
(provided it moves verb_wordnum on by the number of words
it wants to eat up).
Routine returns false
to carry on as usual; true to indicate that the routine
has parsed the entire command itself, and set up action,
noun and second to the appropriate order;
or a dictionary value for a verb, such as 'take', to
indicate “parse the command from this verb's grammar instead”;
or minus such a value, e.g. -'take', to indicate “parse
from this verb and then parse the usual grammar as well”.
initial |
String or routine |
For objects The description of an object
not yet picked up, used when a room is described; or a routine to
print one out.
For rooms Printed or run when the room
is arrived in, either by ordinary movement or by PlayerTo.
Warning If the object is a door,
or a container, or is switchable, then use
one of the when_ properties rather than initial.
No return value
inside_description |
String or routine |
For objects Printed as part or all of
a room description when the player is inside the given object, which
must be enterable.
invent |
Routine |
This routine is for changing an object's inventory
listing. If provided, it's called twice, first with the variable
inventory_stage set to 1, second with it set to 2. At
stage 1, you have an entirely free hand to print a different inventory
listing.
Routine returns Stage 1: false
to continue; true to stop here, printing nothing further
about the object or its contents.
At stage 2, the object's indefinite article and
short name have already been printed, but messages like “ (providing
light)” haven't. This is an opportunity to add something like
“ (almost empty)".
Routine returns Stage 2: false
to continue; true to stop here, printing nothing further
about the object or its contents.
life |
Routine NULL (+) |
This routine holds rules about animate
objects, behaving much like before and after
but only handling the person-to-person events:
Attack Kiss WakeOther ThrowAt Give Show Ask Tell Answer Order
See §17, §18
and the properties orders and grammar.
Routine returns true to
stop and print nothing, false to resume as usual (for
example, printing “Miss Gatsby has better things to do.”).
list_together |
Number, string or routine |
For objects Objects with the same
list_together value are grouped together in object lists
(such as inventories, or the miscellany at the end of a room description).
If a string such as "fish" is given, then such
a group will be headed with text such as "five fish".
A routine, if given, is called at two stages in the
process (once with the variable inventory_stage set to 1,
once with it set to 2). These stages occur before and after the group
is printed; thus, a preamble or postscript can be printed. Also, such
a routine may change the variable c_style (which holds the
current list style). On entry, the variable parser_one holds
the first object in the group, and parser_two the current
depth of recursion in the list. Applying x=NextEntry(x,parser_two);
moves x on from parser_one to the next item
in the group. Another helpful variable is listing_together,
set up to the first object of a group being listed (or to 0 whenever no
group is being listed).
Routine returns Stage 1: false
to continue, true not to print the group's list at all.
Routine returns Stage 2: No return value.
name |
List of dictionary words (+) |
For objects A list of dictionary words
referring to this object.
Warning The parse_name property
of an object may take precedence over this, if present.
For rooms A list of words which the
room understands but which refer to things which “do not need
to be referred to in this game”; these are only looked at if
all other attempts to understand the player's command have failed.
Warning Uniquely in Inform syntax,
these dictionary words are given in double quotes "thus",
whereas in all other circumstances they would be 'thus'. This
means they can safely be only one letter long without ambiguity.
number |
Any value |
A general purpose property left free: conventionally
holding a number like “number of turns' battery power left”.
(Now unnecessary, number is a feature left over from earlier
versions of Inform where it was less easy to make new properties.)
For compass objects Note that the standard
compass objects defined by the library all provide a number property,
in case this might be useful to the designer.
orders |
Routine |
For animate or
talkable objects This carries out the player's
orders (or doesn't, as it sees fit): it looks at actor,
action, noun and second to
do so. Unless this object is the current player, actor is
irrelevant (it is always the player) and the object is the person
being ordered about.
If the player typed an incomprehensible command, like
“robot, og sthou”, then the action is NotUnderstood
and the variable etype holds the parser's error number.
If this object is the current player then actor
is the person being ordered about. actor can either be
this object — in which case an action is being processed, because
the player has typed an ordinary command — or can be some other
object, in which case the player has typed an order. See
§18 for how to write orders routines
in these cases.
Routine returns true to
stop and print nothing further; false to continue. (Unless
the object is the current player, the life routine's
Order section gets an opportunity to meddle next; after
that, Inform gives up.)
parse_name |
Routine |
For objects To parse an object's name
(this overrides the name but is also used in determining if
two objects are describably identical). This routine should try to
match as many words as possible in sequence, reading them one at a
time by calling NextWord(). (It can leave the “word
marker” variable wn anywhere it likes).
Routine returns 0 if the text didn't
make any sense at all, −1 to make the parser resume its usual
course (looking at the name), or the number of words in
a row which successfully matched.
In addition to this, if the text matched seems to
be in the plural (for instance, a blind mouse object reading blind
mice), the routine can set the variable parser_action
to the value ##PluralFound. The parser will then match with
all of the different objects understood, rather than ask a player which
of them is meant.
A parse_name routine may also (voluntarily)
assist the parser by telling it whether or not two objects which share
the same parse_name routine are identical. (They may share
the same routine if they both inherit it from a class.) If, when it is
called, the variable parser_action is set to ##TheSame
then this is the reason. It can then decide whether or not the objects
parser_one and parser_two are indistinguishable.
Routine returns −1 if the objects are indistinguishable, −2 if not.
plural |
String or routine |
For objects The plural name of an object
(when in the presence of others like it), or routine to print one;
for instance, a wax candle might have plural set to
"wax candles".
No return value
react_after |
Routine |
For objects Acts like an after
rule, but detects any actions in the vicinity (any actions which take
place when this object is in scope).
Routine returns true to
print nothing further; false to carry on.
react_before |
Routine |
For objects Acts like a before
rule, but detects any actions in the vicinity (any actions which take
place when this object is in scope).
Routine returns true to
stop the action, printing nothing; false to carry on.
short_name |
Routine |
For objects The short name of an object (like “brass lamp”), or a routine to print it.
Routine returns true to
stop here, false to carry on by printing the object's
‘real’ short name (the string given at the head of the
object's definition). It's sometimes useful to print text like
"half-empty " and then return false.
short_name_indef |
Routine |
For objects If set, this form of the short name is used when the name is prefaced by an indefinite article. (This is not useful in English-language games, but in other languages adjectival parts of names agree with the definiteness of the article.)
time_left |
Number |
Number of turns left until the timer for this object
(if set, which must be done using StartTimer) goes off.
Its initial value is of no significance, as StartTimer will
write over this, but a timer object must provide the property. If
the timer is currently set, the value 0 means “will go off at
the end of the current turn”, the value 1 means “…
at the end of next turn” and so on.
time_out |
Routine NULL (+) |
Routine to run when the timer for this object goes
off (having been set by StartTimer and not in the mean
time stopped by StopTimer).
Warning A timer object must also provide
a time_left property.
when_closed |
String or routine |
For objects Description, or routine
to print one, of something closed (a door or
container) in a room's long description.
No return value
when_open |
String or routine |
For objects Description, or routine
to print one, of something open (a door or
container) in a room's long description.
No return value
when_on |
String or routine |
For objects Description, or routine
to print one, of a switchable object which is currently
switched on, in a room's long description.
No return value
when_off |
String or routine |
For objects Description, or routine
to print one, of a switchable object which is currently
switched off, in a room's long description.
No return value
with_key |
Object nothing |
The key object needed to lock or unlock this
lockable object. A player must explicitly name it as the
key being used and be holding it at the time. The value nothing,
or 0, means that no key fits (though this is not made clear to the
player, who can try as many as he likes).