Ircbgb

An IRC client library.

Installing

Install it through rubygems,

gem install ircbgb

or whatever, by now you know the drill.

Purpose

To refresh my knowledge of RFC 1459 (et al) and to provide the first concrete use case for io_unblock.

Usage

Start a Client

client = Ircbgb::Client.new do |c|
  c.servers = [ 'irc://irc.freenode.net' ]
  c.nicks = [ 'nick1', 'nick2', 'nick3' ]
  c.username = 'user1'
  c.realname = 'I am a test client'
end

client.connect

This will open a socket to irc.freenode.net on port 6667 (by default) and send the required USER, NICK and PONG commands to establish a connection. The io_unblock library handles IO through a separate thread, as a result there is no guarantee that the client is actually connected immediately after client.connect is executed.

Respond to events

client.received :privmsg do |msg, me|
  # `me` == `client`
  $stdout.puts "<#{msg.source.nick}/#{msg.target}> #{msg.text}"
end

client.sent :privmsg do |msg, me|
  $stdout.puts "#{msg.target}> #{msg.text}"
end

Defining custom messages

Ircbgb::Messages.define :privmsg do
  target 0
  text 1
  targets { target.split(',') }
end

Ircbgb::Messages.define :ctcp_request, :privmsg do
  match { |cmd, params, src|
    params[1] =~ /\A\001.*\001\Z/
  }

  request { text[1..-2] }
  ctcp_command { request.split(' ').first }
end

With those definitions in place, if the IRC server sent the following message:

some_dude!dude@my.host.name PRIVMSG #stuff :Testing is fun!

Ircbgb would parse it into an instance of the Privmsg class we just defined:

a_msg.target  #=> "#stuff"
a_msg.text    #=> "Testing is fun!"
a_msg.params  #=> ["#stuf", "Testing is fun!"]
a_msg.command #=> "PRIVMSG"
a_msg.source  #=> Ircbgb::User

The params, command, and source attributes come from Ircbgb::Message, which all defined messages inherit from. Our custom defined messages can do even more!

If you sent the following message:

PRIVMSG some_dude :\001VERSION\001

Ircbgb would parse it into an instance of the CtcpRequest class. The parser resolves the string to a class by first examining the command, PRIVMSG, in this case. It finds a Privmsg class, so now it gives subclasses of Privmsg a chance to claim ownership of the message. As it happens, CtcpRequest is a subclass of Privmsg because we gave :privmsg as the second parameter to Ircbgb::Messages.define. The parser then invokes the match block with the appropriate parameters, in this case "PRIVMSG", "\001VERSION\001" and nil as the client itself is the source. The match block detects the surrounding "\001" characters, and returns true, thus a CtcpRequest is born (instead of a Privmsg or generic Message instance.)

Message definitions can leverage all kinds of neat stuff. I'll write more on that later, in the mean time have a look at specs/ircbgb/messages_spec.rb

Event shortcomings

The implementation is not quite what I want yet.

Currently, we have:

client.received(:privmsg) { ... }

which is equivalent to

client.received('PRIVMSG') { ... }

However,

client.received(:ctcp_request) { ... }

will never get triggered, because Ircbgb triggers based solely on the command name at the moment. Here's an example of what I ultimately want:

client.define(:no_such_nickname, :numeric => 401)

client.received(401) { ... }

client.received(:no_such_nickname) { ... }

I think the way to handle this is to match against the command when a string or fixnum is given to the event binding helpers (sending, sent, receiving, received), and filter by class name when a symbol is given. Further, I need to implement the ability to base a message definition off of a numeric command.

I also want to change how callback chains can be stopped. At the moment, if a callback returns false, no further processing on the chain is performed; however, the :all chain still gets executed. Returning false isn't good enough for me. I would rather have a couple explicit methods, like prevent_default! and halt! where prevent_default! stops the default chain from being executed, and halt! stops any further processing in the current chain. If we wrap the callback evaluation within a kind of CallbackEvent instance, we can provide these two methods, as well as some other goodies.