<p>All in-game objects in Evennia, be it characters, chairs, monsters, rooms or hand grenades are
represented by an Evennia <em>Object</em>. Objects form the core of Evennia and is probably what you’ll
spend most time working with. Objects are <aclass="reference internal"href="Typeclasses.html"><spanclass="doc std std-doc">Typeclassed</span></a> entities.</p>
<p>An Evennia Object is, by definition, a Python class that includes <aclass="reference internal"href="../api/evennia.objects.objects.html#evennia.objects.objects.DefaultObject"title="evennia.objects.objects.DefaultObject"><spanclass="xref myst py py-class">evennia.objects.objects.DefaultObject</span></a> among its parents. Evennia defines several subclasses of <codeclass="docutils literal notranslate"><spanclass="pre">DefaultObject</span></code> in the following inheritance tree:</p>
<p>Here, arrows indicate inheritance and point from-child-to-parent.</p>
<p>So, for example <codeclass="docutils literal notranslate"><spanclass="pre">DefaultObjet</span></code> is a child of <codeclass="docutils literal notranslate"><spanclass="pre">DefaultCharacter</span></code> (in the Evennia library), which is a parent of <codeclass="docutils literal notranslate"><spanclass="pre">Character</span></code> (in the game dir). The class in the game-dir is the one you should modify for your game.</p>
<blockquote>
<div><p>Note the <codeclass="docutils literal notranslate"><spanclass="pre">ObjectParent</span></code> class. This is an empty mix-in that all classes in the game-dir inherits from. It’s where you put things you want <em>all</em> these classes to have.</p>
<li><p><aclass="reference internal"href="../api/evennia.objects.objects.html#evennia.objects.objects.DefaultCharacter"title="evennia.objects.objects.DefaultCharacter"><spanclass="xref myst py py-class">evennia.objects.objects.DefaultCharacter</span></a> - the normal in-game Character, controlled by a player.</p></li>
<li><p><aclass="reference internal"href="../api/evennia.objects.objects.html#evennia.objects.objects.DefaultRoom"title="evennia.objects.objects.DefaultRoom"><spanclass="xref myst py py-class">evennia.objects.objects.DefaultRoom</span></a> - a location in the game world.</p></li>
<li><p><aclass="reference internal"href="../api/evennia.objects.objects.html#evennia.objects.objects.DefaultExit"title="evennia.objects.objects.DefaultExit"><spanclass="xref myst py py-class">evennia.objects.objects.DefaultExit</span></a> - an entity that in a location (usually a Room). It represents a one-way connection to another location.</p></li>
<p>You can easily add your own in-game behavior by either modifying one of the typeclasses in your game dir or by inheriting from them.</p>
<p>You can put your new typeclass directly in the relevant module, or you could organize your code in some other way. Here we assume we make a new module <codeclass="docutils literal notranslate"><spanclass="pre">mygame/typeclasses/flowers.py</span></code>:</p>
<spanclass="s2">"this is called only once, when object is first created"</span>
<spanclass="c1"># add a persistent attribute 'desc'</span>
<spanclass="c1"># to object (silly example).</span>
<spanclass="bp">self</span><spanclass="o">.</span><spanclass="n">db</span><spanclass="o">.</span><spanclass="n">desc</span><spanclass="o">=</span><spanclass="s2">"This is a pretty rose with thorns."</span>
</pre></div>
</div>
<p>Now you just need to point to the class <em>Rose</em> with the <codeclass="docutils literal notranslate"><spanclass="pre">create</span></code> command
<p>What the <codeclass="docutils literal notranslate"><spanclass="pre">create</span></code> command actually <em>does</em> is to use the <aclass="reference internal"href="../api/evennia.utils.create.html#evennia.utils.create.create_object"title="evennia.utils.create.create_object"><spanclass="xref myst py py-func">evennia.create_object</span></a>
function. You can do the same thing yourself in code:</p>
<p>(The <codeclass="docutils literal notranslate"><spanclass="pre">create</span></code> command will auto-append the most likely path to your typeclass, if you enter the
call manually you have to give the full path to the class. The <codeclass="docutils literal notranslate"><spanclass="pre">create.create_object</span></code> function is
powerful and should be used for all coded object creating (so this is what you use when defining
your own building commands).</p>
<p>This particular Rose class doesn’t really do much, all it does it make sure the attribute
<codeclass="docutils literal notranslate"><spanclass="pre">desc</span></code>(which is what the <codeclass="docutils literal notranslate"><spanclass="pre">look</span></code> command looks for) is pre-set, which is pretty pointless since you
will usually want to change this at build time (using the <codeclass="docutils literal notranslate"><spanclass="pre">desc</span></code> command or using the
This is an empty ‘mixin’ class. Optionally, you can modify this class if you want to easily add some <em>common</em> functionality to all your Objects, Characters, Rooms and Exits at once. You can still customize each subclass separately (see the Python docs on <aclass="reference external"href="https://docs.python.org/3/tutorial/classes.html#multiple-inheritance">multiple inheritance</a> for details).</p>
<p>Now all of <codeclass="docutils literal notranslate"><spanclass="pre">Object</span></code>, <codeclass="docutils literal notranslate"><spanclass="pre">Exit</span></code>. <codeclass="docutils literal notranslate"><spanclass="pre">Room</span></code> and <codeclass="docutils literal notranslate"><spanclass="pre">Character</span></code> default to not being able to be picked up using the <codeclass="docutils literal notranslate"><spanclass="pre">get</span></code> command.</p>
<h2>Properties and functions on Objects<aclass="headerlink"href="#properties-and-functions-on-objects"title="Permalink to this headline">¶</a></h2>
<p>Beyond the properties assigned to all <aclass="reference internal"href="Typeclasses.html"><spanclass="doc std std-doc">typeclassed</span></a> objects (see that page for a list
of those), the Object also has the following custom properties:</p>
<li><p><codeclass="docutils literal notranslate"><spanclass="pre">aliases</span></code> - a handler that allows you to add and remove aliases from this object. Use <codeclass="docutils literal notranslate"><spanclass="pre">aliases.add()</span></code> to add a new alias and <codeclass="docutils literal notranslate"><spanclass="pre">aliases.remove()</span></code> to remove one.</p></li>
<li><p><codeclass="docutils literal notranslate"><spanclass="pre">location</span></code> - a reference to the object currently containing this object.</p></li>
<li><p><codeclass="docutils literal notranslate"><spanclass="pre">home</span></code> is a backup location. The main motivation is to have a safe place to move the object to if its <codeclass="docutils literal notranslate"><spanclass="pre">location</span></code> is destroyed. All objects should usually have a home location for safety.</p></li>
<li><p><codeclass="docutils literal notranslate"><spanclass="pre">destination</span></code> - this holds a reference to another object this object links to in some way. Its main use is for <aclass="reference internal"href="#exits"><spanclass="std std-doc">Exits</span></a>, it’s otherwise usually unset.</p></li>
<li><p><codeclass="docutils literal notranslate"><spanclass="pre">nicks</span></code> - as opposed to aliases, a <aclass="reference internal"href="Nicks.html"><spanclass="doc std std-doc">Nick</span></a> holds a convenient nickname replacement for a real name, word or sequence, only valid for this object. This mainly makes sense if the Object is used as a game character - it can then store briefer shorts, example so as to quickly reference game commands or other characters. Use nicks.add(alias, realname) to add a new one.</p></li>
<li><p><codeclass="docutils literal notranslate"><spanclass="pre">account</span></code> - this holds a reference to a connected <aclass="reference internal"href="Accounts.html"><spanclass="doc std std-doc">Account</span></a> controlling this object (if any). Note that this is set also if the controlling account is <em>not</em> currently online - to test if an account is online, use the <codeclass="docutils literal notranslate"><spanclass="pre">has_account</span></code> property instead.</p></li>
<li><p><codeclass="docutils literal notranslate"><spanclass="pre">sessions</span></code> - if <codeclass="docutils literal notranslate"><spanclass="pre">account</span></code> field is set <em>and the account is online</em>, this is a list of all active sessions (server connections) to contact them through (it may be more than one if multiple connections are allowed in settings).</p></li>
<li><p><codeclass="docutils literal notranslate"><spanclass="pre">has_account</span></code> - a shorthand for checking if an <em>online</em> account is currently connected to this object.</p></li>
<li><p><codeclass="docutils literal notranslate"><spanclass="pre">contents</span></code> - this returns a list referencing all objects ‘inside’ this object (i,e. which has this object set as their <codeclass="docutils literal notranslate"><spanclass="pre">location</span></code>).</p></li>
<li><p><codeclass="docutils literal notranslate"><spanclass="pre">exits</span></code> - this returns all objects inside this object that are <em>Exits</em>, that is, has the <codeclass="docutils literal notranslate"><spanclass="pre">destination</span></code> property set.</p></li>
<li><p><codeclass="docutils literal notranslate"><spanclass="pre">cmdset</span></code> - this is a handler that stores all <aclass="reference internal"href="Command-Sets.html"><spanclass="doc std std-doc">command sets</span></a> defined on the object (if any).</p></li>
<li><p><codeclass="docutils literal notranslate"><spanclass="pre">scripts</span></code> - this is a handler that manages <aclass="reference internal"href="Scripts.html"><spanclass="doc std std-doc">Scripts</span></a> attached to the object (if any).</p></li>
<p>The Object also has a host of useful utility functions. See the function headers in <codeclass="docutils literal notranslate"><spanclass="pre">src/objects/objects.py</span></code> for their arguments and more details.</p>
<li><p><codeclass="docutils literal notranslate"><spanclass="pre">msg()</span></code> - this function is used to send messages from the server to an account connected to this object.</p></li>
<li><p><codeclass="docutils literal notranslate"><spanclass="pre">msg_contents()</span></code> - calls <codeclass="docutils literal notranslate"><spanclass="pre">msg</span></code> on all objects inside this object.</p></li>
<li><p><codeclass="docutils literal notranslate"><spanclass="pre">search()</span></code> - this is a convenient shorthand to search for a specific object, at a given location or globally. It’s mainly useful when defining commands (in which case the object executing the command is named <codeclass="docutils literal notranslate"><spanclass="pre">caller</span></code> and one can do <codeclass="docutils literal notranslate"><spanclass="pre">caller.search()</span></code> to find objects in the room to operate on).</p></li>
<li><p><codeclass="docutils literal notranslate"><spanclass="pre">execute_cmd()</span></code> - Lets the object execute the given string as if it was given on the command line.</p></li>
<li><p><codeclass="docutils literal notranslate"><spanclass="pre">move_to</span></code> - perform a full move of this object to a new location. This is the main move method and will call all relevant hooks, do all checks etc.</p></li>
<li><p><codeclass="docutils literal notranslate"><spanclass="pre">clear_exits()</span></code> - will delete all <aclass="reference internal"href="#exits"><spanclass="std std-doc">Exits</span></a> to <em>and</em> from this object.</p></li>
<li><p><codeclass="docutils literal notranslate"><spanclass="pre">clear_contents()</span></code> - this will not delete anything, but rather move all contents (except Exits) to their designated <codeclass="docutils literal notranslate"><spanclass="pre">Home</span></code> locations.</p></li>
<li><p><codeclass="docutils literal notranslate"><spanclass="pre">delete()</span></code> - deletes this object, first calling <codeclass="docutils literal notranslate"><spanclass="pre">clear_exits()</span></code> and <codeclass="docutils literal notranslate"><spanclass="pre">clear_contents()</span></code>.</p></li>
<p>The Object Typeclass defines many more <em>hook methods</em> beyond <codeclass="docutils literal notranslate"><spanclass="pre">at_object_creation</span></code>. Evennia calls these hooks at various points. When implementing your custom objects, you will inherit from the base parent and overload these hooks with your own custom code. See <codeclass="docutils literal notranslate"><spanclass="pre">evennia.objects.objects</span></code> for an updated list of all the available hooks or the <aclass="reference internal"href="../api/evennia.objects.objects.html#evennia.objects.objects.DefaultObject"title="evennia.objects.objects.DefaultObject"><spanclass="xref myst py py-class">API for DefaultObject here</span></a>.</p>
<h2>Subclasses of <codeclass="docutils literal notranslate"><spanclass="pre">Object</span></code><aclass="headerlink"href="#subclasses-of-object"title="Permalink to this headline">¶</a></h2>
<p>There are three special subclasses of <em>Object</em> in default Evennia - <em>Characters</em>, <em>Rooms</em> and <em>Exits</em>. The reason they are separated is because these particular object types are fundamental, something you will always need and in some cases requires some extra attention in order to be recognized by the game engine (there is nothing stopping you from redefining them though). In practice they are all pretty similar to the base Object.</p>
<p>Characters are objects controlled by <aclass="reference internal"href="Accounts.html"><spanclass="doc std std-doc">Accounts</span></a>. When a new Account logs in to Evennia for the first time, a new <codeclass="docutils literal notranslate"><spanclass="pre">Character</span></code> object is created and the Account object is assigned to the <codeclass="docutils literal notranslate"><spanclass="pre">account</span></code> attribute. A <codeclass="docutils literal notranslate"><spanclass="pre">Character</span></code> object must have a <aclass="reference internal"href="Command-Sets.html"><spanclass="doc std std-doc">Default Commandset</span></a> set on itself at creation, or the account will not be able to issue any commands! If you just inherit your own class from <codeclass="docutils literal notranslate"><spanclass="pre">evennia.DefaultCharacter</span></code> and make sure to use <codeclass="docutils literal notranslate"><spanclass="pre">super()</span></code> to call the parent methods you should be fine. In <codeclass="docutils literal notranslate"><spanclass="pre">mygame/typeclasses/characters.py</span></code> is an empty <codeclass="docutils literal notranslate"><spanclass="pre">Character</span></code> class ready for you to modify.</p>
<p><em>Rooms</em> are the root containers of all other objects. The only thing really separating a room from any other object is that they have no <codeclass="docutils literal notranslate"><spanclass="pre">location</span></code> of their own and that default commands like <codeclass="docutils literal notranslate"><spanclass="pre">@dig</span></code> creates objects of this class - so if you want to expand your rooms with more functionality, just inherit from <codeclass="docutils literal notranslate"><spanclass="pre">ev.DefaultRoom</span></code>. In <codeclass="docutils literal notranslate"><spanclass="pre">mygame/typeclasses/rooms.py</span></code> is an empty <codeclass="docutils literal notranslate"><spanclass="pre">Room</span></code> class ready for you to modify.</p>
<p><em>Exits</em> are objects connecting other objects (usually <em>Rooms</em>) together. An object named <em>North</em> or <em>in</em> might be an exit, as well as <em>door</em>, <em>portal</em> or <em>jump out the window</em>. An exit has two things that separate them from other objects. Firstly, their <em>destination</em> property is set and points to a valid object. This fact makes it easy and fast to locate exits in the database. Secondly, exits define a special <aclass="reference internal"href="Commands.html"><spanclass="doc std std-doc">Transit Command</span></a> on themselves when they are created. This command is named the same as the exit object and will, when called, handle the practicalities of moving the character to the Exits’s <em>destination</em> - this allows you to just enter the name of the exit on its own to move around, just as you would expect.</p>
<p>The exit functionality is all defined on the Exit typeclass, so you could in principle completely change how exits work in your game (it’s not recommended though, unless you really know what you are doing). Exits are <aclass="reference internal"href="Locks.html"><spanclass="doc std std-doc">locked</span></a> using an access_type called <em>traverse</em> and also make use of a few hook methods for giving feedback if the traversal fails. See <codeclass="docutils literal notranslate"><spanclass="pre">evennia.DefaultExit</span></code> for more info. In <codeclass="docutils literal notranslate"><spanclass="pre">mygame/typeclasses/exits.py</span></code> there is an empty <codeclass="docutils literal notranslate"><spanclass="pre">Exit</span></code> class for you to modify.</p>
<li><p>The traversing <codeclass="docutils literal notranslate"><spanclass="pre">obj</span></code> sends a command that matches the Exit-command name on the Exit object. The <aclass="reference internal"href="Commands.html"><spanclass="doc std std-doc">cmdhandler</span></a> detects this and triggers the command defined on the Exit. Traversal always involves the “source” (the current location) and the <codeclass="docutils literal notranslate"><spanclass="pre">destination</span></code> (this is stored on the Exit object).</p></li>
<li><p>In <codeclass="docutils literal notranslate"><spanclass="pre">at_traverse</span></code>, <codeclass="docutils literal notranslate"><spanclass="pre">object.move_to(destination)</span></code> is triggered. This triggers the following hooks, in order:</p>
<li><p><codeclass="docutils literal notranslate"><spanclass="pre">obj.at_pre_move(destination)</span></code> - if this returns False, move is aborted.</p></li>
<li><p>Move is performed by changing <codeclass="docutils literal notranslate"><spanclass="pre">obj.location</span></code> from source location to <codeclass="docutils literal notranslate"><spanclass="pre">destination</span></code>.</p></li>
<li><p>On the Exit object, <codeclass="docutils literal notranslate"><spanclass="pre">at_post_traverse(obj,</span><spanclass="pre">source)</span></code> is triggered.</p></li>
<p>If the move fails for whatever reason, the Exit will look for an Attribute <codeclass="docutils literal notranslate"><spanclass="pre">err_traverse</span></code> on itself and display this as an error message. If this is not found, the Exit will instead call <codeclass="docutils literal notranslate"><spanclass="pre">at_failed_traverse(obj)</span></code> on itself.</p>
