-% Inform in four minutes
+o% Inform in four minutes
% Roger Firth <roger@firthworks.com>
A quick reference to the Inform programming language.
A property variable inherited from an object's class is
addressed by *object.class::property*; this gives the
original value prior to any changes within the object.
+
+Manipulating the object tree
+----------------------------
+
+To change object relationships at run-time:
+
+ move object to parent_object ;
+ remove object ;
+
+To return the parent of an object (or nothing):
+
+ parent(object)
+
+To return the first child of an object (or nothing):
+
+ child(object)
+
+To return the adjacent child of an object's parent (or nothing):
+
+ sibling(object)
+
+To return the number of child objects directly below an object:
+
+ children(object)
+
+Message passing
+---------------
+
+To a class:
+
+ class.remaining()
+ class.create()
+ class.destroy(object)
+ class.recreate(object)
+ class.copy(to_object,from_object)
+
+To an object:
+
+ object.property(a1,a2, ... a7)
+
+To a routine:
+
+ routine.call(a1,a2, ... a7)
+
+To a string:
+
+ string.print()
+ 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;
\ No newline at end of file