The Object Model

Building

The Object Model

Everything in a MUSH is an object. Rooms, exits, things, and players are all objects in the database, distinguished by type but sharing a common set of properties. Understanding the object model is fundamental to building and programming in MUSH.

Object Types

There are four object types:

Type	Created By	Purpose
Room	`@dig`	A location that contains other objects and has exits
Exit	`@open`	A link between rooms (or to other objects)
Thing	`@create`	An inanimate object that can be carried, dropped, and manipulated
Player	`@pcreate` / `create`	An animate object controlled by a human

The type letter appears after the dbref in examine output: R for room, E for exit, P for player, and no letter for things.

Dbrefs

Every object has a unique database reference number (dbref), written as # followed by a number: #0, #1, #1234. Dbrefs are assigned sequentially when objects are created and are recycled when objects are destroyed.

Special dbrefs:

Dbref	Meaning
`#0`	The master room (Limbo)
`#1`	God—the first player, with absolute power
`#-1`	NOTHING—indicates no object (failed match, no location, etc.)
`#-2`	AMBIGUOUS—multiple objects matched a name
`#-3`	HOME—a symbolic reference to an object’s home location

Because dbrefs are recycled, a dbref that referred to your favorite sword yesterday might refer to someone else’s room today if the sword was destroyed. Use objid() for persistent references—it includes a creation timestamp that detects recycled dbrefs.

Properties

Every object has these intrinsic properties:

Name – the display name. Exits can have multiple semicolon-separated aliases.
Location – where the object is. Rooms have no location (or are in #-1). Exits are located in their source room.
Contents – a linked list of objects inside this one. Rooms contain things, players, and other objects. Players and things can contain things.
Exits – a linked list of exits attached to this object (primarily rooms, but any object can have exits via @open).
Home – where the object goes when sent home. Players have a home room. Things have a home location.
Owner – the player who owns this object. Players own themselves.
Parent – an optional parent object for attribute inheritance.
Zone – an optional zone master object for group control.
Flags – a set of boolean flags (DARK, STICKY, WIZARD, etc.).
Powers – a set of granted capabilities (see Powers List).
Attributes – named key-value pairs storing data and code.

Containment

The containment model is simple: every object (except rooms) is inside exactly one other object. This forms a tree:

Room #100
├── Player #5 (Bob)
│   ├── Thing #200 (sword)
│   └── Thing #201 (shield)
├── Thing #300 (fountain)
└── Exit #400 (north -> #101)

Objects move between containers via commands like get, drop, enter, leave, goto, and @teleport. Each movement triggers a sequence of messages and attribute actions (see Moving).

Attribute Inheritance

If an object has a parent (set with @parent), it inherits attributes from that parent. When the server looks up an attribute, it checks the object first, then the parent, then the parent’s parent, up to a configurable depth (usually 10 levels).

Inheritance is read-only: changing an attribute on the parent affects all children that don’t override it. Setting an attribute on a child creates a local copy that shadows the parent’s version.

Exits on parent objects also appear in children. This is how zone-wide global exits work.

The Object Lifecycle

Creation: @create, @dig, @open, or @pcreate allocates a dbref. The lowest available recycled dbref is used first; if none are available, a new one is allocated at the end of the database.
Active use: The object exists, can be examined, modified, and interacted with.
Destruction: @destroy marks the object as GOING. After a configurable delay (or immediately with /instant), the object becomes GARBAGE—its attributes are cleared and its dbref is available for recycling.

The SAFE flag protects objects from accidental destruction. The DESTROY_OK flag allows anyone who controls the object to destroy it without confirmation.

Related Topics: Object Types, Dbref, Attribute, Zones, Parent Objects.