<pclass="last">You are reading an old version of the Evennia documentation. <ahref="https://www.evennia.com/docs/latest/index.html">The latest version is here</a></p>.
<h1>Tutorial for basic MUSH like game<aclass="headerlink"href="#tutorial-for-basic-mush-like-game"title="Permalink to this headline">¶</a></h1>
<p>This tutorial lets you code a small but complete and functioning MUSH-like game in Evennia. A
<aclass="reference external"href="https://en.wikipedia.org/wiki/MUSH">MUSH</a> is, for our purposes, a class of roleplay-centric games
focused on free form storytelling. Even if you are not interested in MUSH:es, this is still a good
first game-type to try since it’s not so code heavy. You will be able to use the same principles for
building other types of games.</p>
<p>The tutorial starts from scratch. If you did the <aclass="reference internal"href="Beginner-Tutorial/Part1/Beginner-Tutorial-Part1-Overview.html"><spanclass="doc std std-doc">First Steps Coding</span></a> tutorial
already you should have some ideas about how to do some of the steps already.</p>
<p>The following are the (very simplistic and cut-down) features we will implement (this was taken from
a feature request from a MUSH user new to Evennia). A Character in this system should:</p>
<ulclass="simple">
<li><p>Have a “Power” score from 1 to 10 that measures how strong they are (stand-in for the stat
system).</p></li>
<li><p>Have a command (e.g. <codeclass="docutils literal notranslate"><spanclass="pre">+setpower</span><spanclass="pre">4</span></code>) that sets their power (stand-in for character generation
code).</p></li>
<li><p>Have a command (e.g. <codeclass="docutils literal notranslate"><spanclass="pre">+attack</span></code>) that lets them roll their power and produce a “Combat Score”
between <codeclass="docutils literal notranslate"><spanclass="pre">1</span></code> and <codeclass="docutils literal notranslate"><spanclass="pre">10*Power</span></code>, displaying the result and editing their object to record this number
(stand-in for <codeclass="docutils literal notranslate"><spanclass="pre">+actions</span></code> in the command code).</p></li>
<li><p>Have a command that displays everyone in the room and what their most recent “Combat Score” roll
was (stand-in for the combat code).</p></li>
<li><p>Have a command (e.g. <codeclass="docutils literal notranslate"><spanclass="pre">+createNPC</span><spanclass="pre">Jenkins</span></code>) that creates an NPC with full abilities.</p></li>
<li><p>Have a command to control NPCs, such as <codeclass="docutils literal notranslate"><spanclass="pre">+npc/cmd</span><spanclass="pre">(name)=(command)</span></code> (stand-in for the NPC
controlling code).</p></li>
</ul>
<p>In this tutorial we will assume you are starting from an empty database without any previous
modifications.</p>
<sectionid="server-settings">
<h2>Server Settings<aclass="headerlink"href="#server-settings"title="Permalink to this headline">¶</a></h2>
<p>To emulate a MUSH, the default <codeclass="docutils literal notranslate"><spanclass="pre">MULTISESSION_MODE=0</span></code> is enough (one unique session per
account/character). This is the default so you don’t need to change anything. You will still be able
to puppet/unpuppet objects you have permission to, but there is no character selection out of the
box in this mode.</p>
<p>We will assume our game folder is called <codeclass="docutils literal notranslate"><spanclass="pre">mygame</span></code> henceforth. You should be fine with the default
SQLite3 database.</p>
</section>
<sectionid="creating-the-character">
<h2>Creating the Character<aclass="headerlink"href="#creating-the-character"title="Permalink to this headline">¶</a></h2>
<p>First thing is to choose how our Character class works. We don’t need to define a special NPC object
– an NPC is after all just a Character without an Account currently controlling them.</p>
<p>Make your changes in the <codeclass="docutils literal notranslate"><spanclass="pre">mygame/typeclasses/characters.py</span></code> file:</p>
<p>We defined two new <aclass="reference internal"href="../Components/Attributes.html"><spanclass="doc std std-doc">Attributes</span></a><codeclass="docutils literal notranslate"><spanclass="pre">power</span></code> and <codeclass="docutils literal notranslate"><spanclass="pre">combat_score</span></code> and set them to default
values. Make sure to <codeclass="docutils literal notranslate"><spanclass="pre">@reload</span></code> the server if you had it already running (you need to reload every
time you update your python code, don’t worry, no accounts will be disconnected by the reload).</p>
<p>Note that only <em>new</em> characters will see your new Attributes (since the <codeclass="docutils literal notranslate"><spanclass="pre">at_object_creation</span></code> hook is
called when the object is first created, existing Characters won’t have it). To update yourself,
<p>This resets your own typeclass (the <codeclass="docutils literal notranslate"><spanclass="pre">/force</span></code> switch is a safety measure to not do this
accidentally), this means that <codeclass="docutils literal notranslate"><spanclass="pre">at_object_creation</span></code> is re-run.</p>
<p>Under the “Persistent attributes” heading you should now find the new Attributes <codeclass="docutils literal notranslate"><spanclass="pre">power</span></code> and <codeclass="docutils literal notranslate"><spanclass="pre">score</span></code>
set on yourself by <codeclass="docutils literal notranslate"><spanclass="pre">at_object_creation</span></code>. If you don’t, first make sure you <codeclass="docutils literal notranslate"><spanclass="pre">@reload</span></code>ed into the new
code, next look at your server log (in the terminal/console) to see if there were any syntax errors
in your code that may have stopped your new code from loading correctly.</p>
</section>
<sectionid="character-generation">
<h2>Character Generation<aclass="headerlink"href="#character-generation"title="Permalink to this headline">¶</a></h2>
<p>We assume in this example that Accounts first connect into a “character generation area”. Evennia
also supports full OOC menu-driven character generation, but for this example, a simple start room
is enough. When in this room (or rooms) we allow character generation commands. In fact, character
generation commands will <em>only</em> be available in such rooms.</p>
<p>Note that this again is made so as to be easy to expand to a full-fledged game. With our simple
example, we could simply set an <codeclass="docutils literal notranslate"><spanclass="pre">is_in_chargen</span></code> flag on the account and have the <codeclass="docutils literal notranslate"><spanclass="pre">+setpower</span></code> command
check it. Using this method however will make it easy to add more functionality later.</p>
<p>What we need are the following:</p>
<ulclass="simple">
<li><p>One character generation <aclass="reference internal"href="../Components/Commands.html"><spanclass="doc std std-doc">Command</span></a> to set the “Power” on the <codeclass="docutils literal notranslate"><spanclass="pre">Character</span></code>.</p></li>
<li><p>A chargen <aclass="reference internal"href="../Components/Command-Sets.html"><spanclass="doc std std-doc">CmdSet</span></a> to hold this command. Lets call it <codeclass="docutils literal notranslate"><spanclass="pre">ChargenCmdset</span></code>.</p></li>
<li><p>A custom <codeclass="docutils literal notranslate"><spanclass="pre">ChargenRoom</span></code> type that makes this set of commands available to players in such rooms.</p></li>
<li><p>One such room to test things in.</p></li>
</ul>
<sectionid="the-setpower-command">
<h3>The +setpower command<aclass="headerlink"href="#the-setpower-command"title="Permalink to this headline">¶</a></h3>
<p>For this tutorial we will add all our new commands to <codeclass="docutils literal notranslate"><spanclass="pre">mygame/commands/command.py</span></code> but you could
split your commands into multiple module if you prefered.</p>
<p>For this tutorial character generation will only consist of one <aclass="reference internal"href="../Components/Commands.html"><spanclass="doc std std-doc">Command</span></a> to set the
Character s “power” stat. It will be called on the following MUSH-like form:</p>
<p>Open <codeclass="docutils literal notranslate"><spanclass="pre">command.py</span></code> file. It contains documented empty templates for the base command and the
“MuxCommand” type used by default in Evennia. We will use the plain <codeclass="docutils literal notranslate"><spanclass="pre">Command</span></code> type here, the
<codeclass="docutils literal notranslate"><spanclass="pre">MuxCommand</span></code> class offers some extra features like stripping whitespace that may be useful - if so,
just import from that instead.</p>
<p>Add the following to the end of the <codeclass="docutils literal notranslate"><spanclass="pre">command.py</span></code> file:</p>
<divclass="highlight-python notranslate"><divclass="highlight"><pre><span></span><spanclass="c1"># end of command.py</span>
<spanclass="kn">from</span><spanclass="nn">evennia</span><spanclass="kn">import</span><spanclass="n">Command</span><spanclass="c1"># just for clarity; already imported above</span>
<spanclass="bp">self</span><spanclass="o">.</span><spanclass="n">caller</span><spanclass="o">.</span><spanclass="n">msg</span><spanclass="p">(</span><spanclass="sa">f</span><spanclass="s2">"Your Power was set to </span><spanclass="si">{</span><spanclass="n">power</span><spanclass="si">}</span><spanclass="s2">."</span><spanclass="p">)</span>
</pre></div>
</div>
<p>This is a pretty straightforward command. We do some error checking, then set the power on ourself.
We use a <codeclass="docutils literal notranslate"><spanclass="pre">help_category</span></code> of “mush” for all our commands, just so they are easy to find and separate
in the help list.</p>
<p>Save the file. We will now add it to a new <aclass="reference internal"href="../Components/Command-Sets.html"><spanclass="doc std std-doc">CmdSet</span></a> so it can be accessed (in a full
chargen system you would of course have more than one command here).</p>
<p>Open <codeclass="docutils literal notranslate"><spanclass="pre">mygame/commands/default_cmdsets.py</span></code> and import your <codeclass="docutils literal notranslate"><spanclass="pre">command.py</span></code> module at the top. We also
import the default <codeclass="docutils literal notranslate"><spanclass="pre">CmdSet</span></code> class for the next step:</p>
<p>Next scroll down and define a new command set (based on the base <codeclass="docutils literal notranslate"><spanclass="pre">CmdSet</span></code> class we just imported at
the end of this file, to hold only our chargen-specific command(s):</p>
<divclass="highlight-python notranslate"><divclass="highlight"><pre><span></span><spanclass="c1"># end of default_cmdsets.py</span>
<p>Note how new rooms created with this typeclass will always start with <codeclass="docutils literal notranslate"><spanclass="pre">ChargenCmdset</span></code> on themselves.
Don’t forget the <codeclass="docutils literal notranslate"><spanclass="pre">persistent=True</span></code> keyword or you will lose the cmdset after a server reload. For
more information about <aclass="reference internal"href="../Components/Command-Sets.html"><spanclass="doc std std-doc">Command Sets</span></a> and <aclass="reference internal"href="../Components/Commands.html"><spanclass="doc std std-doc">Commands</span></a>, see the respective
links.</p>
</section>
<sectionid="testing-chargen">
<h3>Testing chargen<aclass="headerlink"href="#testing-chargen"title="Permalink to this headline">¶</a></h3>
<p>First, make sure you have <codeclass="docutils literal notranslate"><spanclass="pre">@reload</span></code>ed the server (or use <codeclass="docutils literal notranslate"><spanclass="pre">evennia</span><spanclass="pre">reload</span></code> from the terminal) to have
your new python code added to the game. Check your terminal and fix any errors you see - the error
traceback lists exactly where the error is found - look line numbers in files you have changed.</p>
<p>We can’t test things unless we have some chargen areas to test. Log into the game (you should at
this point be using the new, custom Character class). Let’s dig a chargen area to test.</p>
<p>If you read the help for <codeclass="docutils literal notranslate"><spanclass="pre">@dig</span></code> you will find that this will create a new room named <codeclass="docutils literal notranslate"><spanclass="pre">chargen</span></code>. The
part after the <codeclass="docutils literal notranslate"><spanclass="pre">:</span></code> is the python-path to the Typeclass you want to use. Since Evennia will
automatically try the <codeclass="docutils literal notranslate"><spanclass="pre">typeclasses</span></code> folder of our game directory, we just specify
<codeclass="docutils literal notranslate"><spanclass="pre">rooms.ChargenRoom</span></code>, meaning it will look inside the module <codeclass="docutils literal notranslate"><spanclass="pre">rooms.py</span></code> for a class named
<codeclass="docutils literal notranslate"><spanclass="pre">ChargenRoom</span></code> (which is what we created above). The names given after <codeclass="docutils literal notranslate"><spanclass="pre">=</span></code> are the names of exits to
and from the room from your current location. You could also append aliases to each one name, such
as <codeclass="docutils literal notranslate"><spanclass="pre">chargen;character</span><spanclass="pre">generation</span></code>.</p>
<p>So in summary, this will create a new room of type ChargenRoom and open an exit <codeclass="docutils literal notranslate"><spanclass="pre">chargen</span></code> to it and
an exit back here named <codeclass="docutils literal notranslate"><spanclass="pre">finish</span></code>. If you see errors at this stage, you must fix them in your code.
<p>This should bring you to the chargen room. Being in there you should now have the <codeclass="docutils literal notranslate"><spanclass="pre">+setpower</span></code>
command available, so test it out. When you leave (via the <codeclass="docutils literal notranslate"><spanclass="pre">finish</span></code> exit), the command will go away
and trying <codeclass="docutils literal notranslate"><spanclass="pre">+setpower</span></code> should now give you a command-not-found error. Use <codeclass="docutils literal notranslate"><spanclass="pre">ex</span><spanclass="pre">me</span></code> (as a privileged
user) to check so the <codeclass="docutils literal notranslate"><spanclass="pre">Power</span></code><aclass="reference internal"href="../Components/Attributes.html"><spanclass="doc std std-doc">Attribute</span></a> has been set correctly.</p>
<p>If things are not working, make sure your typeclasses and commands are free of bugs and that you
have entered the paths to the various command sets and commands correctly. Check the logs or command
line for tracebacks and errors.</p>
</section>
</section>
<sectionid="combat-system">
<h2>Combat System<aclass="headerlink"href="#combat-system"title="Permalink to this headline">¶</a></h2>
<p>We will add our combat command to the default command set, meaning it will be available to everyone
at all times. The combat system consists of a <codeclass="docutils literal notranslate"><spanclass="pre">+attack</span></code> command to get how successful our attack is.
We also change the default <codeclass="docutils literal notranslate"><spanclass="pre">look</span></code> command to display the current combat score.</p>
<sectionid="attacking-with-the-attack-command">
<h3>Attacking with the +attack command<aclass="headerlink"href="#attacking-with-the-attack-command"title="Permalink to this headline">¶</a></h3>
<p>Attacking in this simple system means rolling a random “combat score” influenced by the <codeclass="docutils literal notranslate"><spanclass="pre">power</span></code> stat
<p>Go back to <codeclass="docutils literal notranslate"><spanclass="pre">mygame/commands/command.py</span></code> and add the command to the end like this:</p>
<spanclass="n">message_template</span><spanclass="o">=</span><spanclass="s2">"</span><spanclass="si">{attacker}</span><spanclass="s2"> +attack</span><spanclass="si">{s}</span><spanclass="s2"> with a combat score of </span><spanclass="si">{c_score}</span><spanclass="s2">!"</span>
<p>What we do here is simply to generate a “combat score” using Python’s inbuilt <codeclass="docutils literal notranslate"><spanclass="pre">random.randint()</span></code>
function. We then store that and echo the result to everyone involved.</p>
<p>To make the <codeclass="docutils literal notranslate"><spanclass="pre">+attack</span></code> command available to you in game, go back to
<codeclass="docutils literal notranslate"><spanclass="pre">mygame/commands/default_cmdsets.py</span></code> and scroll down to the <codeclass="docutils literal notranslate"><spanclass="pre">CharacterCmdSet</span></code> class. At the correct
<p><codeclass="docutils literal notranslate"><spanclass="pre">@reload</span></code> Evennia and the <codeclass="docutils literal notranslate"><spanclass="pre">+attack</span></code> command should be available to you. Run it and use e.g. <codeclass="docutils literal notranslate"><spanclass="pre">@ex</span></code> to
make sure the <codeclass="docutils literal notranslate"><spanclass="pre">combat_score</span></code> attribute is saved correctly.</p>
</section>
<sectionid="have-look-show-combat-scores">
<h3>Have “look” show combat scores<aclass="headerlink"href="#have-look-show-combat-scores"title="Permalink to this headline">¶</a></h3>
<p>Players should be able to view all current combat scores in the room. We could do this by simply
adding a second command named something like <codeclass="docutils literal notranslate"><spanclass="pre">+combatscores</span></code>, but we will instead let the default
<codeclass="docutils literal notranslate"><spanclass="pre">look</span></code> command do the heavy lifting for us and display our scores as part of its normal output, like
this:</p>
<divclass="highlight-none notranslate"><divclass="highlight"><pre><span></span>> look Tom
Tom (combat score: 3)
This is a great warrior.
</pre></div>
</div>
<p>We don’t actually have to modify the <codeclass="docutils literal notranslate"><spanclass="pre">look</span></code> command itself however. To understand why, take a look
at how the default <codeclass="docutils literal notranslate"><spanclass="pre">look</span></code> is actually defined. It sits in <aclass="reference internal"href="../api/evennia.commands.default.general.html#evennia-commands-default-general"><spanclass="std std-ref">evennia/commands/default/general.py</span></a>.</p>
<p>You will find that the actual return text is done by the <codeclass="docutils literal notranslate"><spanclass="pre">look</span></code> command calling a <em>hook method</em>
named <codeclass="docutils literal notranslate"><spanclass="pre">return_appearance</span></code> on the object looked at. All the <codeclass="docutils literal notranslate"><spanclass="pre">look</span></code> does is to echo whatever this hook
returns. So what we need to do is to edit our custom Character typeclass and overload its
<codeclass="docutils literal notranslate"><spanclass="pre">return_appearance</span></code> to return what we want (this is where the advantage of having a custom typeclass
comes into play for real).</p>
<p>Go back to your custom Character typeclass in <codeclass="docutils literal notranslate"><spanclass="pre">mygame/typeclasses/characters.py</span></code>. The default
implementation of <codeclass="docutils literal notranslate"><spanclass="pre">return</span><spanclass="pre">appearance</span></code> is found in <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.DefaultCharacter</span></a>.</p>
<p>If you want to make bigger changes you could copy & paste the whole default thing into our overloading method. In our case the change is small though:</p>
<p>What we do is to simply let the default <codeclass="docutils literal notranslate"><spanclass="pre">return_appearance</span></code> do its thing (<codeclass="docutils literal notranslate"><spanclass="pre">super</span></code> will call the
parent’s version of the same method). We then split out the first line of this text, append our
<codeclass="docutils literal notranslate"><spanclass="pre">combat_score</span></code> and put it back together again.</p>
<p><codeclass="docutils literal notranslate"><spanclass="pre">@reload</span></code> the server and you should be able to look at other Characters and see their current combat
scores.</p>
<blockquote>
<div><p>Note: A potentially more useful way to do this would be to overload the entire <codeclass="docutils literal notranslate"><spanclass="pre">return_appearance</span></code>
of the <codeclass="docutils literal notranslate"><spanclass="pre">Room</span></code>s of your mush and change how they list their contents; in that way one could see all
combat scores of all present Characters at the same time as looking at the room. We leave this as an
exercise.</p>
</div></blockquote>
</section>
</section>
<sectionid="npc-system">
<h2>NPC system<aclass="headerlink"href="#npc-system"title="Permalink to this headline">¶</a></h2>
<p>Here we will re-use the Character class by introducing a command that can create NPC objects. We
should also be able to set its Power and order it around.</p>
<p>There are a few ways to define the NPC class. We could in theory create a custom typeclass for it
and put a custom NPC-specific cmdset on all NPCs. This cmdset could hold all manipulation commands.
Since we expect NPC manipulation to be a common occurrence among the user base however, we will
instead put all relevant NPC commands in the default command set and limit eventual access with
<aclass="reference internal"href="../Components/Permissions.html"><spanclass="doc std std-doc">Permissions and Locks</span></a>.</p>
<sectionid="creating-an-npc-with-createnpc">
<h3>Creating an NPC with +createNPC<aclass="headerlink"href="#creating-an-npc-with-createnpc"title="Permalink to this headline">¶</a></h3>
<p>We need a command for creating the NPC, this is a very straightforward command:</p>
<divclass="highlight-none notranslate"><divclass="highlight"><pre><span></span>> +createnpc Anna
You created the NPC 'Anna'.
</pre></div>
</div>
<p>At the end of <codeclass="docutils literal notranslate"><spanclass="pre">command.py</span></code>, create our new command:</p>
<spanclass="c1"># may not create npc when OOC</span>
<spanclass="n">caller</span><spanclass="o">.</span><spanclass="n">msg</span><spanclass="p">(</span><spanclass="s2">"You must have a location to create an npc."</span><spanclass="p">)</span>
<spanclass="k">return</span>
<spanclass="c1"># make name always start with capital letter</span>
<spanclass="n">locks</span><spanclass="o">=</span><spanclass="sa">f</span><spanclass="s2">"edit:id(</span><spanclass="si">{</span><spanclass="n">caller</span><spanclass="o">.</span><spanclass="n">id</span><spanclass="si">}</span><spanclass="s2">) and perm(Builders);call:false()"</span><spanclass="p">)</span>
<spanclass="c1"># announce</span>
<spanclass="n">message_template</span><spanclass="o">=</span><spanclass="s2">"</span><spanclass="si">{creator}</span><spanclass="s2"> created the NPC '</span><spanclass="si">{npc}</span><spanclass="s2">'."</span>
<p>Here we define a <codeclass="docutils literal notranslate"><spanclass="pre">+createnpc</span></code> (<codeclass="docutils literal notranslate"><spanclass="pre">+createNPC</span></code> works too) that is callable by everyone <em>not</em> having the
<codeclass="docutils literal notranslate"><spanclass="pre">nonpcs</span></code> “<aclass="reference internal"href="../Components/Permissions.html"><spanclass="doc std std-doc">permission</span></a>” (in Evennia, a “permission” can just as well be used to
block access, it depends on the lock we define). We create the NPC object in the caller’s current
location, using our custom <codeclass="docutils literal notranslate"><spanclass="pre">Character</span></code> typeclass to do so.</p>
<p>We set an extra lock condition on the NPC, which we will use to check who may edit the NPC later –
we allow the creator to do so, and anyone with the Builders permission (or higher). See
<aclass="reference internal"href="../Components/Locks.html"><spanclass="doc std std-doc">Locks</span></a> for more information about the lock system.</p>
<p>Note that we just give the object default permissions (by not specifying the <codeclass="docutils literal notranslate"><spanclass="pre">permissions</span></code> keyword
to the <codeclass="docutils literal notranslate"><spanclass="pre">create_object()</span></code> call). In some games one might want to give the NPC the same permissions
as the Character creating them, this might be a security risk though.</p>
<p>Add this command to your default cmdset the same way you did the <codeclass="docutils literal notranslate"><spanclass="pre">+attack</span></code> command earlier.
<codeclass="docutils literal notranslate"><spanclass="pre">@reload</span></code> and it will be available to test.</p>
</section>
<sectionid="editing-the-npc-with-editnpc">
<h3>Editing the NPC with +editNPC<aclass="headerlink"href="#editing-the-npc-with-editnpc"title="Permalink to this headline">¶</a></h3>
<p>Since we re-used our custom character typeclass, our new NPC already has a <em>Power</em> value - it
defaults to 1. How do we change this?</p>
<p>There are a few ways we can do this. The easiest is to remember that the <codeclass="docutils literal notranslate"><spanclass="pre">power</span></code> attribute is just a
simple <aclass="reference internal"href="../Components/Attributes.html"><spanclass="doc std std-doc">Attribute</span></a> stored on the NPC object. So as a Builder or Admin we could set this
right away with the default <codeclass="docutils literal notranslate"><spanclass="pre">@set</span></code> command:</p>
<p>The <codeclass="docutils literal notranslate"><spanclass="pre">@set</span></code> command is too generally powerful though, and thus only available to staff. We will add a
custom command that only changes the things we want players to be allowed to change. We could in
principle re-work our old <codeclass="docutils literal notranslate"><spanclass="pre">+setpower</span></code> command, but let’s try something more useful. Let’s make a
<p>This is a slightly more complex command. It goes at the end of your <codeclass="docutils literal notranslate"><spanclass="pre">command.py</span></code> file as before.</p>
<spanclass="n">caller</span><spanclass="o">.</span><spanclass="n">msg</span><spanclass="p">(</span><spanclass="s2">"You cannot change this NPC."</span><spanclass="p">)</span>
<spanclass="c1"># this means we just list the values</span>
<spanclass="n">output</span><spanclass="o">=</span><spanclass="sa">f</span><spanclass="s2">"Properties of </span><spanclass="si">{</span><spanclass="n">npc</span><spanclass="o">.</span><spanclass="n">key</span><spanclass="si">}</span><spanclass="s2">:"</span>
<spanclass="n">caller</span><spanclass="o">.</span><spanclass="n">msg</span><spanclass="p">(</span><spanclass="s2">"You may only change </span><spanclass="si">%s</span><spanclass="s2">."</span><spanclass="o">%</span>
<p>This command example shows off the use of more advanced parsing but otherwise it’s mostly error
checking. It searches for the given npc in the same room, and checks so the caller actually has
permission to “edit” it before continuing. An account without the proper permission won’t even be
able to view the properties on the given NPC. It’s up to each game if this is the way it should be.</p>
<p>Add this to the default command set like before and you should be able to try it out.</p>
<p><em>Note: If you wanted a player to use this command to change an on-object property like the NPC’s
name (the <codeclass="docutils literal notranslate"><spanclass="pre">key</span></code> property), you’d need to modify the command since “key” is not an Attribute (it is
not retrievable via <codeclass="docutils literal notranslate"><spanclass="pre">npc.attributes.get</span></code> but directly via <codeclass="docutils literal notranslate"><spanclass="pre">npc.key</span></code>). We leave this as an optional
<h3>Making the NPC do stuff - the +npc command<aclass="headerlink"href="#making-the-npc-do-stuff-the-npc-command"title="Permalink to this headline">¶</a></h3>
<p>Finally, we will make a command to order our NPC around. For now, we will limit this command to only
be usable by those having the “edit” permission on the NPC. This can be changed if it’s possible for
anyone to use the NPC.</p>
<p>The NPC, since it inherited our Character typeclass has access to most commands a player does. What
it doesn’t have access to are Session and Player-based cmdsets (which means, among other things that
they cannot chat on channels, but they could do that if you just added those commands). This makes
the <codeclass="docutils literal notranslate"><spanclass="pre">+npc</span></code> command simple:</p>
<divclass="highlight-none notranslate"><divclass="highlight"><pre><span></span>+npc Anna = say Hello!
Anna says, 'Hello!'
</pre></div>
</div>
<p>Again, add to the end of your <codeclass="docutils literal notranslate"><spanclass="pre">command.py</span></code> module:</p>
<spanclass="n">caller</span><spanclass="o">.</span><spanclass="n">msg</span><spanclass="p">(</span><spanclass="s2">"You may not order this NPC to do anything."</span><spanclass="p">)</span>
<spanclass="n">caller</span><spanclass="o">.</span><spanclass="n">msg</span><spanclass="p">(</span><spanclass="sa">f</span><spanclass="s2">"You told </span><spanclass="si">{</span><spanclass="n">npc</span><spanclass="o">.</span><spanclass="n">key</span><spanclass="si">}</span><spanclass="s2"> to do '</span><spanclass="si">{</span><spanclass="bp">self</span><spanclass="o">.</span><spanclass="n">cmdname</span><spanclass="si">}</span><spanclass="s2">'."</span><spanclass="p">)</span>
</pre></div>
</div>
<p>Note that if you give an erroneous command, you will not see any error message, since that error
will be returned to the npc object, not to you. If you want players to see this, you can give the
caller’s session ID to the <codeclass="docutils literal notranslate"><spanclass="pre">execute_cmd</span></code> call, like this:</p>
<p>Another thing to remember is however that this is a very simplistic way to control NPCs. Evennia
supports full puppeting very easily. An Account (assuming the “puppet” permission was set correctly)
could simply do <codeclass="docutils literal notranslate"><spanclass="pre">@ic</span><spanclass="pre">mynpc</span></code> and be able to play the game “as” that NPC. This is in fact just what
happens when an Account takes control of their normal Character as well.</p>
</section>
</section>
<sectionid="concluding-remarks">
<h2>Concluding remarks<aclass="headerlink"href="#concluding-remarks"title="Permalink to this headline">¶</a></h2>
<p>This ends the tutorial. It looks like a lot of text but the amount of code you have to write is
actually relatively short. At this point you should have a basic skeleton of a game and a feel for
what is involved in coding your game.</p>
<p>From here on you could build a few more ChargenRooms and link that to a bigger grid. The <codeclass="docutils literal notranslate"><spanclass="pre">+setpower</span></code>
command can either be built upon or accompanied by many more to get a more elaborate character
generation.</p>
<p>The simple “Power” game mechanic should be easily expandable to something more full-fledged and
useful, same is true for the combat score principle. The <codeclass="docutils literal notranslate"><spanclass="pre">+attack</span></code> could be made to target a
specific player (or npc) and automatically compare their relevant attributes to determine a result.</p>
<p>To continue from here, you can take a look at the <aclass="reference internal"href="Beginner-Tutorial/Part1/Beginner-Tutorial-Tutorial-World.html"><spanclass="doc std std-doc">Tutorial World</span></a>. For
more specific ideas, see the <aclass="reference internal"href="Howtos-Overview.html"><spanclass="doc std std-doc">other tutorials and hints</span></a> as well
as the <aclass="reference internal"href="../Components/Components-Overview.html"><spanclass="doc std std-doc">Evennia Component overview</span></a>.</p>
<pclass="last">You are reading an old version of the Evennia documentation. <ahref="https://www.evennia.com/docs/latest/index.html">The latest version is here</a></p>.
