Limnoria/docs/EXAMPLE

Here's an example of how to code a few callbacks for SupyBot.

Let's say you want to make an annoying "Mimic" callback that repeats everything
anyone says to the bot or on the channels the bot is in.  That
shouldn't be too hard.  First, you'll need to make a new module to
hold the plugin:

$ scripts/newplugin.py Mimic

That'll make the file plugins/Mimic.py, which will 


[code]
class AnnoyingMimic(irclib.IrcCallback):
    def doPrivmsg(self, irc, msg):
        irc.queueMsg(ircmsgs.privmsg(msg.args[0], msg.args[1]))
[/code]

Almost every callback will inherit from irclib.IrcCallback somewhere in their
class hierarchy.  irclib.IrcCallback does a lot of the basic stuff that call-
backs have to do, and inheriting from it relieves the programmer from such
pedantries.  All you have to do to start writing callbacks inheriting from
irclib.IrcCallback is write functions of the form "doCommand", where "Command"
is a valid ircCommand.  The "ChannelLogger" plugin is a good illustrative
example of a callback being called on different commands.

The "irc" argument there is the irc object that is calling the callback.  To
see what kind of interface it provides, read the class definition in irclib.
Really, you only need to know a few methods if you're writing simple callbacks:
'queueMsg', which queues a message to be sent later, and 'sendMsg' which tries
to send it right away (well, as soon as the Irc object's driver asks for
another message to send, which is generally right away).  The Irc object also
provides some attributes that might come in useful, most notably "nick" (the
nick of the bot) and "state" (an IrcState object that does various useful
things like keeping a history of the most recent irc messages.)

Irc messsages are represented by the IrcMsg class in ircmsgs.  It has several
useful methods and attributes, but it's probably easier for you to read the
code than for me to tell you about it.  The ircmsgs module also provides a set
of useful little commands to create IrcMsg objects that do particular little
things; for instance, ircmsgs.privmsg(recipient, msg) sends a PRIVMSG command
to a channel or user (whatever recipient turns out to be).  Check out the code
to see other functions for making IrcMsg objects.

Now, that wasn't too bad.  Now, however you're going to have to get it into the
bot.  Note that AnnoyingMimic doesn't have an __init__.  This'll make it pretty
simple to get it into the configuration system.  Look for the section of the
config file where you see all the configurations for Irc objects.  These
configurations are going to be lists of (class name, args, kwargs) tuples which
contain the name of a callback class to be instantiated, a tuple of the argu-
ments to be passed to the __init__ function for that class, and a dictionary
of the keyword arguments to be passed to the __init__ function of that class.
For instance, if AnnoyingMimic was in a file 'mycallbacks.py', its config-
uration in the config file would look like this:

[code]
('mycallbacks.AnnoyingMimic', (), {})
[/code]

Since it doesn't have an __init__, there are no arguments or keyword arguments
to pass to the class.  Just throw something like that in a list of callbacks
that you use for your bot (you can have several lists, you'll notice later on
in the 'drivers' variable that they're used), and you're ready to go!

Now, let's say you want to make your AnnoyingMimic class a little less
annoying.  Now, you only want to mimic people *you* find annoying.  The easiest
way to do that is to make it so you tell the class who to mimic when you
instantiate it.  This means adding an __init__ function, and modifying your
configuration slightly.

[code]
class AnnoyingMimic(irclib.IrcCallback):
    def __init__(self, nicksToAnnoy):
        self.nicksToAnnoy = nicksToAnnoy

    def doPrivmsg(self, irc, msg):
        if msg.nick() in self.nicksToAnnoy:
            irc.queueMsg(ircmsgs.privmsg(msg.args[0], msg.args[1]))
[/code]

(Now, really, to make this efficient, you'd want a slightly different version
that turned the nicksToAnnoy argument into a dictionary so nick lookups would
be O(1) instead of O(n) in the length of the list of nicks to annoy, but that
would obfuscate the problem.  I'll leave that as an exercise left up to the
reader.)

So now your AnnoyingMimic class has an __init__ function that accepts a list
of nicks to annoy, but how do you pass it those nicks?  Simple!  Change the
configuration slightly:

[code]
('mycallbacks.AnnoyingMimic', (['jemfinch', 'GnuVince'],), {})
[/code]

That's the wonder of this configuration system -- you can use all the Python
syntax you want, so you have practically unlimited flexibility.

(Note that since the 'arguments' member of that tuple is a single-member tuple,
you'll have to stick a comma after the first (only) element because otherwise
Python wouldn't believe it's a tuple.)

So, again, you choose to make your AnnoyingMimic less annoying -- really, you
decide to make it not annoying at all by making it only mimic people who ask to
be repeated.  You want to make a class that has an "echo" command that repeats
the message to those who ask it.  You want people to be able to tell the bot,
"echo The quick brown fox jumps over the lazy dog!" and have the bot say right
back, "The quick brown fox jumps over the lazy dog!".  That's easy!  Here's the
code:

[code]
reply = callbacks.reply

class Echo(callbacks.Privmsg):
    def echo(self, irc, msg, args):
        "<text>"
        text = self.getArgs(args)
        self.reply(text)
[/code]

So that seemed pretty simple there, too.  Let's explain what's going on:

callbacks.Privmsg is an easy way to create "commands" which are simple named
functions that use a universal scheme for delimiting arguments -- basically,
they'll all act the same in how they get their arguments.  callbacks.Privmsg
takes a Privmsg (it has a doPrivmsg function and inherits from
irclib.IrcCallback) and first determines if it's addressed to the bot -- the
message must either be PRIVMSGed directly to the bot, or PRIVMSGed over a
channel the bot is in and either start with a character in conf.prefixchars or
start with the bot's name.  Don't worry, callbacks.Privmsg almost always does
The Right Thing.  After deciding that the bot has been addressed,
callbacks.Privmsg then parses the text of the message into a list of strings.
Here are a few examples of what it would do:

"""arg1 arg2 arg3"""
['arg1', 'arg2', 'arg3']

"""'arg1 arg2 arg3' arg4""" # Note the quotes.
['arg1 arg2 arg3', 'arg4']

getArgs is a function that just a little bit of magic.  It takes an optional
argument (that defaults to 1) of the number of args needed.  If more than one
argument is needed, it checks that the proper number of arguments has been
given, and then returns a tuple of those arguments.  So if you wanted 3 args
from a message, you'd do something like this:

(name, oldpassword, newpassword) = self.getArgs(args, 3)

See how simple that is?  If getArgs only needs one argument, however, it does
something a bit magic -- first of all, it doesn't return a tuple, it just
returns the argument itself.  This makes it so you can type:

text = self.getArgs(args)

Instead of:

(text,) = self.getArgs(args)

It just makes things easier that way.  Also, however, if *only* one argument
is needed, it does something a bit more magical.  A lot of commands take only
one argument and then do some processing on it -- for example, look at the
privmsgs module, the "FunCommands" callback, at the commands 'leet' and
'rot13'.  This is all great, but because of the way args are normally parsed
by callbacks.Privmsg, you'd have to always enclose that argument in quotes.
For instance, you'd have to type this:

bot: leet "The quick brown fox jumps over the lazy dog."

From experience, I can tell you that most people will forget the quotes almost
every time they talk to the bot.  Since having only one argument is such a
command case, getArgs special-cases it to string.join all the args with spaces.
Now you can say:

bot: leet The quick brown fox jumps over the lazy dog.

And it'll return the same exact thing as above.  Of course, the original still
works, but since people forget the quotes so often, it's good to go easy on
them :)  We're actually using that behavior with our callback above: by using
getArgs, now our users can say:

echo foo bar baz

Instead of always having to say:

echo "foo bar baz"

Anyway, you're probably wondering how that callback works.  It inherits from
callbacks.Privmsg, which as I mentioned before, has a doPrivmsg callback.  So
when callbacks.Privmsg receives a PRIVMSG command, it parses it and then tries
to find if it has a method by the same name as the command -- if it does, and
that method looks like this:

def method(self, irc, msg, args):
    ...

Then it calls that method with the appropriate arguments.  Easy, huh?  Don't
worry, it gets even cooler :)  So you write a command like echo and you want
to provide the user with some help using it.  You were probably wondering why
the docstring to that "echo" method above looked so weird, but now you know:
it *is* the help for the command!  callbacks.Privmsg has its own command, help,
which will return the *docstring* for any other command!  So it's cake to write
your own commands and help.

(This, of course, means that if you *don't* write a help string for your
command, you have no excuse and are just plain lazy.  So write help strings!)

There's a bit more I could tutorialize on, but it would be more esoteric, and
better a reference material than as a tutorial.  I'll put that in another file.