Build Your Own Bot

Okay, so this dumb bot can’t do much, can it? You want something more exciting?

Want a more clever bot?

Here’s how:

  • Create a module / script with a bot that extends the core bot
  • add it a few “do_[stuff]” commands
  • make it more clever, by using its “brain”

You can see a few example of what a “brainy bot” can do, remember by browsing the bots available in the “samples” directory.

Detailed example: brainybot

BrainyBot is a class that resides in the samples directory. Let’s dive in its code:

from cmdbot.core import Bot, direct

class BrainyBot(Bot):

    def do_hello(self, line):
        "Reply hello and save that in brain"
        self.say("%s: hello" % line.nick_from)
        self.brain.who_said_hello_last = line.nick_from

    def do_who(self, line):
        "Tell us who talked to you last"
        if self.brain.knows('who_said_hello_last'):
            self.say("The one that talked to me last: %s" % self.brain.who_said_hello_last)
            self.say("Nobody has talked to me...")

Since BrainyBot extends the Bot class, it already knows how to “ping” and how to “help” you. If we run it (using an appopriate ‘.ini’ file), and try to talk to it, here is some result:

22:53 -!- cmdbot [~cmdbot@] has joined #cdc
22:53 < cmdbot> Hi everyone.
22:54 < No`> cmdbot: hello
22:54 < cmdbot> No`: hello
22:54 < No`> cmdbot: who
22:54 < cmdbot> The one that talked to me last: No`

We’ve used the Brain of our Bot, to tell it to store in-memory who’s talked to him last. And by asking it who, it’s able to tell it to us.

Please note the knows() method, that returns True if the brain has an “interesting” value (i.e. not “None”, or empty string, list, tuple, etc). You can just test wether the lookuped key is present in the brain by using the optional include_falses argument:

>>> bot.brain.knows('stuff')
>>> bot.brain.stuff = ''
>>> bot.brain.knows('stuff')
>>> bot.brain.knows('stuff', include_falses=True)
>>> bot.brain.stuff = 'hello'
>>> bot.brain.knows('stuff')

The do_<trick>

You may have noticed that every new thing your bot knows to do is prefixed by do_. That’s the trick. When someone on the channel says something, the bot analyses it. If the first word of the message is a verb your bot knows about, the do_<verb> action is processed:


This behaviour is heavily borrowed on the Python cmd module.

The decorators


Whenever a do_ method is decorated by @direct, it will only be executed if someone is directly talking to the Bot:

def do_hello(self, line):
    self.say('hello, you')
22:53 -!- cmdbot [~cmdbot@] has joined #cdc
22:53 < cmdbot> Hi everyone.
22:54 < No`> hello
22:54 < No`> cmdbot: hello
22:54 < cmdbot> hello, you

The first time, the user didn’t talk directly to the bot. The second time, it was mentioned, so the bot replied “hello, you”


When a do_ is decorated by @admin the code will only be executed if the previous lines has been said by an admin:

def do_hello(self, line):
    self.say('hello, my lord')
22:53 -!- cmdbot [~cmdbot@] has joined #cdc
22:53 < cmdbot> Hi everyone.
22:54 < NotAdmin> hello
22:54 < AdminUser> hello
22:54 < cmdbot> hello, my lord


You’ve noticed that it doesn’t have to be direct. It’s only if the verb it the first word of the message.

And what about “no decorator”

Without decorator, the do_<stuff> method will be called each time a line is being said by a user. Beware, then, your bot may have a lot of work to do...

And what happens if we mix them?

There comes the beauty of decorators. You can mix them:

def do_hello(self, line):
    self.say('hello, my lord')

The bot will then only say “hello my lord” if some admin directly told it “hello”.

Your own decorator

Right. You can “prefix” any action with your own decorator, if you want this action to be called only following a certain condition or a subset of conditions. Your “Bot’s Brain” might help. Here’s a simple example, taken from the samples/

def in_game(func):
    "Decorator: only process the line game has been started with the player"
    def newfunc(bot, line):
        if bot.brain.knows('games') and line.nick_from in
            return func(bot, line)
            bot.say("Erm. Looks like we didn't start playing.")
    return newfunc

In this snippet, we’re defining a decorator that will only process the command if the “game” has been started with the player.

After that, you can use the decorator like this:

def do_roll(self, line):
    # ...

Bonus: the welcome message

Each bot says something when it /joins the chan. If you want a custom message, just do something like:

class FrenchBot(Bot):
    welcome_message = "Bonjour tout le monde !"

The Configuration you want

CmdBot is coming with two available configuration modules. The default one is using the “ini file” described in the ini file section.

But you can override this using the ArgumentConfiguration. Like this:

from cmdbot.core import Bot
from cmdbot.configs import ArgumentConfiguration

class ArgumentBot(Bot):
    config_class = ArgumentConfiguration

That’s it. If you want, you can build your own configuration module. All you have to do is to build one that has at least the following available properties (if not mentioned, should be a string):

  • host
  • chan
  • port - should be an int
  • nick
  • ident
  • realname
  • admins - should be a tuple, a list or any iterable

What’s next?

Well... now, the sky is the limit. Extended bots can manipulate data, remember it, treat and process it... And you can still use this bot as a “dumb” one, if you want!

You can also make your own decorators, exactly the way @admin() and @direct() work. You may, for example... change the behaviour of a command if your brain contains a certain bit of data, or if the first letter of the nick is a “Z”... you see?... no. limit.

A few more examples will probably appear in the samples directory. Stay tuned!