-o% Inform in four minutes
+% Inform in four minutes
% Roger Firth <roger@firthworks.com>
A quick reference to the Inform programming language.
---------------- ----------------------------------------
*p == q* *p* is equal to *q*
*p ~= q* *p* isn't equal to *q*
- *p* > *q* *p* is greater than *q*
- *p < q* *p* is less than *q*
- *p >= q* *p* is greater than or equal to *q*
- *p <= q* *p* is less than or equal to *q*
+ *p* > *q* *p* is greater than *q*
+ *p < q* *p* is less than *q*
+ *p >= q* *p* is greater than or equal to *q*
+ *p <= q* *p* is less than or equal to *q*
*p ofclass q* object *p* is of class *q*
*p in q* object *p* is a child of object *q*
*p notin q* object *p* isn't a child of object *q*
Array array --> "string";
A **table array** is a set of global words accessed using
-*array-->1*, *array-->2*, ... *array-->N*, with
-*array-->0* initialized to *N*:
+*array-->1*, *array-->2*, ... *array-->N*, with
+*array-->0* initialized to *N*:
Array array table N ;
Array array table expr1 expr2 ... exprN
Array array table "string";
A **byte array** is a set of global bytes accessed using
-*array->0*, *array->1*, ... *array->(N-1)*:
+*array->0*, *array->1*, ... *array->(N-1)*:
Array array -> N;
Array array -> expr1 expr2 ... exprN;
Array array -> "string";
A **string array** is a set of global bytes accessed using
-*array->1*, *array->2*, ... *array->N*, with *array->0*
+*array->1*, *array->2*, ... *array->N*, with *array->0*
initialized to *N*:
Array array string N;
To a string:
string.print()
- string.print_to_array(array)
\ No newline at end of file
+ string.print_to_array(array)
+
+Statements
+----------
+
+Each *statement* is terminated by a semi-colon ";".
+
+A *statement_block* is a single *statement* or a series of
+*statements* enclosed in braces {...}.
+
+An exclamation "!" starts a comment - rest of line ignored.
+
+A common statement is the assignment:
+
+ variable = expr ;
+
+There are two forms of multiple assignment:
+
+ variable = variable = ... = expr ;
+ variable = expr, variable = expr, ... ;
+
+Routines
+--------
+
+A routine can have up to 15 local variables: word values which are
+private to the routine and which by default are set to zero on each
+call. Recursion is permitted.
+
+A **standalone** routine:
+
+- has a name, by which it is called using `routine();` can also be
+ called indirectly using
+
+ indirect(routine,a1,a2, ... a7)
+
+- can take arguments, using `routine(a1,a2, ... a7)`, whose values
+ initialise the equivalent local variables
+
+- returns true at the final "]"
+
+ [ routine
+ local_var local_var ... local_var ;
+ statement;
+ statement;
+ ...
+ statement;
+ ]
+
+A routine **embedded** as the value of an object property:
+
+- has no name, and is called when the property is invoked; can also
+ be called explicitly using object.property()
+
+- accepts arguments only when called explicitly
+
+- returns false at the final "]"
+
+ property [
+ local_var local_var ... local_var;
+ statement;
+ statement;
+ ...
+ statement;
+ ]
+
+Routines return a single value, when execution reaches the final "\]"
+or an explicit return statement:
+
+ return expr;
+ return;
+ rtrue;
+ rfalse;
+
+To define a dummy standalone routine with N local variables (unless it
+already exists):
+
+ Stub routine N;
+
+Flow control
+------------
+
+To execute statements if *expr* is true; optionally, to execute other
+statements if *expr* is false:
+
+ if (expr)
+ statement_block
+ if (expr)
+ statement_block
+ else
+ statement_block
+
+To execute statements depending on the value of *expr*:
+
+ switch (expr) {
+ value: statement; ... statement;
+ value: statement; ... statement;
+ ...
+ default: statement; ... statement;
+ }
+
+where each *value* can be given as:
+
+ constant
+ lo_constant to hi_constant
+ constant,constant, ... constant
+
+Loop control
+------------
+
+To execute statements while *expr* is true:
+
+ while (expr)
+ statement_block
+
+To execute statements until *expr* is true:
+
+ do
+ statement_block
+ until (expr)
+
+To execute statements while a variable changes:
+
+ for (set_var : loop_while_expr : update_var )
+ statement_block
+
+To execute statements for all defined objects:
+
+ objectloop (variable)
+ statement_block
+
+To execute statements for all objects selected by *expr*:
+
+ objectloop (expr_starting_with_variable)
+ statement_block
+
+To jump out of the current innermost loop or switch:
+
+ break;
+
+To immediately start the next iteration of the current loop:
+
+ continue;
+
+Displaying information
+----------------------
+
+To output a list of values:
+
+ print value,value, ... value;
+
+To output a list of values followed by a newline, then return `true`
+from the current routine:
+
+ print_ret value,value, ... value;
+
+If the first (or only) *value* is a string, "`print_ret`" can be
+omitted:
+
+ "string",value, ... value ;
+
+Each *value* can be an expression, a string or a rule.
+
+An **expression** is output as a signed decimal value.
+
+A **string** in quotes "..." is output as text.
+
+A **rule** is one of:
+
+ -------------------- ------------------------------------------------
+ `(number)` *expr* the *expr* in words
+ `(char)` *expr* the *expr* as a single character
+ `(string)` *addr* the string at the *addr*
+ `(address)` *addr* the dictionary word at the *addr*
+ `(name)` *object* the external (short) name of the object
+ `(a)` *object* the short name preceded by "a/an"
+ `(the)` *object* the short name preceded by "the"
+ `(The)` *object* the short name preceded by "The"
+ `(routine)` value the output when calling `routine(value)`
+ -------------------- ------------------------------------------------
+
+To output a newline character:
+
+ new_line;
+
+To output multiple spaces:
+
+ spaces expr;
+
+To output text in a display box:
+
+ box "string " "string " ... "string ";
+
+To change from regular to fixed-pitch font:
+
+ font off;
+ ...
+ font on;
+
+To change the font attributes:
+
+ style bold; ! use one or more of these
+ style underline ; !
+ style reverse ; !
+ ...
+ style roman;
+
+Uncommon and deprecated statements
+----------------------------------
+
+To jump to a labelled statement:
+
+ jump label;
+ ...
+ .label; statement;
+
+To terminate the program:
+
+ quit
+
+To save and restore the program state:
+
+ save label;
+ ...
+ restore label;
+
+To output the Inform compiler version number:
+
+inversion;
+
+To accept data from the current input stream:
+
+ read text_array parse_array routine;
+
+To assign to one of 32 'low string' variables:
+
+ string N "string";
+ Lowstring string_var "string";
+ string N string_var;
+
+Verbs and Actions
+-----------------
+
+To specify a new verb:
+
+ Verb 'verb ' 'verb ' ... 'verb '
+ * token token ... token -> action
+ * token token ... token -> action
+ ...
+ * token token ... token -> action;
+
+where instead "`Verb`" can be "`Verb meta`", "*action*" can be
+"`action reverse`"; *tokens* are optional and each is one of:
+
+ ----------------- ----------------------------------------------
+ 'word' that literal word
+ 'w1'/'w2'/... any one of those literal words
+ attribute an object with that attribute
+ creature an object with `animate` attribute
+ held an object held by the player
+ noun an object in scope
+ noun=`routine` an object for which *routine* returns `true`
+ scope=`routine` an object in this re-definition of scope
+ multiheld one or more objects held by the player
+ multi one or more objects in scope
+ multiexcept as multi, omitting the specified object
+ multiinside as multi, omitting those in specified object
+ topic any text
+ number any number
+ routine a general parsing routine
+ ----------------- ----------------------------------------------
+
+To add synonyms to an existing verb:
+
+ Verb 'verb ' 'verb ' ... = 'existing_verb';
+
+To modify an existing verb:
+
+ Extend 'existing_verb ' last
+ * token token ... token –> action
+ * token token ... token –> action
+ ...
+ * token token ... token –> action ;
+
+where instead "`Extend`" can be "`Extend only`" and "`last`" can be
+omitted, or changed to "`first`" or "`replace`"
+
+To explicitly trigger a defined action (both *noun* and *second* are
+optional, depending on the action):
+
+ <action noun second>;
+
+To explicitly trigger a defined action, then return `true` from the
+current routine:
+
+ <<action noun second >>;
+
+Other useful directives
+-----------------------
+
+To include a directive within a routine definition \[...\], insert a
+hash "\#" as its first character.
+
+To conditionally compile:
+
+ Ifdef name; ! use any one of these
+ Ifndef name; !
+ Iftrue expr; !
+ Iffalse expr; !
+ ...
+ Ifnot;
+ ...
+ Endif;
+
+To display a compile-time message:
+
+ Message "string";
+
+To include the contents of a file, searching the Library path:
+
+ Include "source_file";
+
+To include the contents of a file in the same location as the current
+file:
+
+ Include ">source_file";
+
+To specify that a library routine is to be replaced:
+
+ Replace routine;
+
+To set the game's release number (default is 1), serial number
+(default is today's *yymmdd*) and status line format (default is
+`score`):
+
+ Release expr;
+ Serial "yymmdd";
+ Statusline score;
+ Statusline time;
+
+To declare a new attribute common to all objects:
+
+ Attribute attribute ;
+
+To declare a new property common to all objects:
+
+ Property property;
+ Property property expr;
\ No newline at end of file
projects / inform-resources.git / blobdiff