Editing Inform (section)

=== The Inform 6 programming language ===

The Inform programming language is [[Object-oriented programming|object-oriented]] and [[procedural programming|procedural]]. A key element of the language is objects. Objects are maintained in an object tree which lists the parent–child relationships between objects. Since the parent–child relationship is often used to represent location, an object which is the parent of another object is often said to "hold" it. Objects can be moved throughout the tree. Typically, top level objects represent rooms and other locations within the game, which may hold objects representing the room's contents, be they physical items, non-player characters, the player's character, or background effects. All objects can hold other objects, so a <code>livingroom</code> object might hold an <code>insurancesaleman</code> object which is holding a <code>briefcase</code> object which contains the <code>insurancepaperwork</code> object.

In early versions of Inform, objects were different from the notion of objects from object-oriented programming, in that there was no such thing as a class. Later versions added support for class definitions and allowed objects to be members of classes. Objects and classes can inherit from multiple classes. Interactive fiction games typically contain many unique objects. Because of this, many objects in Inform do not inherit from any class, other than the "metaclass" Object. However, objects very frequently have attributes (boolean properties, such as <code>scenery</code> or <code>edible</code>) that are recognized by the Inform library. In other languages this would normally be implemented via inheritance.

Here is a simple example of Inform 6 source code.
<syntaxhighlight lang="inform6">
! Square brackets define a routine. This is the Main routine, which takes no arguments.
[ Main;
    print "Hello, World!^";
];
</syntaxhighlight>

The procedual parts, statements and operators, are largely borrowed from C, with the notable exception that {{code|-->x}} instead of {{code|[x]}} is used to take array subscripts. Routines are defined in square brackets, as in the {{code|Main}} routine above,<ref name=Plotkin/> but called with round brackets as in C. The character {{code|@}} is used to [[escape character]]s and to invoke raw Z-machine opcodes.<ref>{{cite web |title=The Inform Designer's Manual, v4, Contents |url=https://www.inform-fiction.org/manual/html/contents.html |website=www.inform-fiction.org}}</ref>