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Basics Tutorial

Table of Contents

• Blog Tutorial

• Subscribing to Events

  • Event Handler Input

• Responding to Events

  • Example: Echo Bot

• Generating Messages

• Up Next

This tutorial covers basic usage of IRC::Client, without going into all of the supported events or describing all of the methods or available Message Objects. This should be enough if you're just bringing some functionality using IRC as your interface, rather than making, say, a full-featured IRC client.

Blog Tutorial

There exists a blog post describing this bot and showcasing some of the more advanced features. You can find it at yet to be published.

Subscribing to Events

All of the functionality is implemented as "plugins", which are passed to the :plugins attribute. Plugins are just regular classes, altough they can do the IRC::Client::Plugin role to obtain extra functionality.

To subscribe to one of the events, simply create a method with the event's name in your class. The tutorial will use the irc-to-me event, which is a convenience event fired when the bot is addressed in-channel or someone sends it a notice or a private message.

Event Handler Input

The event handlers receive one positional argument, which is an object that does the IRC::Client::Message role. The actual object received depends on the event that triggered the handler. For example, the irc-to-me can receive these message objects:

    IRC::Client::Message::Privmsg::Me
    IRC::Client::Message::Privmsg::Channel
    IRC::Client::Message::Notice::Me
    IRC::Client::Message::Notice::Channel

While message objects differ in methods they offer, all of the above do have a .text attribute and stringify to its value. This means we can add a type constraint on it without having to explicitly call it:

    method irc-to-me ($e where /'bot command'/) { 'Do things here!'; }

Responding to Events

Channel messages, private messages, and notices can be replied to. Their message objects have a .reply method you can call to send a reply to the message's sender. However, it's easier to just return a value from your method handler, which will automatically call .reply on the message object for you.

Returning a value from your event handler signals to the Client Object that it handled the event and no other plugins or event handlers should be tried. Your plugin can do the IRC::Client::Plugin role (automatically exported when you use IRC::Client), which provides $.NEXT attribute. The value of that attribute is special and returning it signals the Client Object that your event handler did not handle the event and other plugins and event handlers should be tried.

Here are the things your event handler can return:

• Value of $.NEXT: pass the event to the next plugin or event handler than can handle it

• Nil (and a select few other items that don't make sense as replies, such as IRC::Client object): do not reply to the message, but do not pass the event to any other event handler; we handled it

• Promise: when the Promise is .kept, use its value for the .reply, unless it's a Nil. Note: you cannot return $.NEXT here.

• Any other value: mark the event as handled and don't pass it further. The returned value will be given to message object's .reply method if it has one, or ignored if it doesn't. For irc-to-me message objects, this means the value will be sent back to the sender of the original message

Example: Echo Bot

In this example, we subscribe to the irc-to-me event and respond by returning the original message, prefixed with You said .

    use IRC::Client;

    .run with IRC::Client.new:
        :host<irc.freenode.net>
        :channels('#rakubot', '#zofbot', '#myown' => 's3cret')
        :debug
        :plugins(
            class { method irc-to-me ($e) { "You said $e.text()"} }
        )

Generating Messages

If your plugin needs to generate messages instead of merely responding to commands, you can use the Client Object's .send method. Your plugin needs to do the IRC::Client::Plugin role to get access to the Client Object via the $.irc attribute:

use IRC::Client;

class AlarmBot does IRC::Client::Plugin {
    method irc-connected ($) {
        react {
            whenever Supply.interval(3) {
                $.irc.send: :where<#raku> :text<Three seconds passed!>;
            }
        }
    }
}

.run with IRC::Client.new:
    :nick<MahBot>
    :host<irc.freenode.net>
    :channels<#raku>
    :debug
    :plugins(AlarmBot.new)

Here, we subscribe to the irc-connected event (using an anonymous parameter for its message object, since we don't need it). It fires whenever we successfully connect to a server. In the event handler we setup a react/whenever loop, with a Supply generating an event every three seconds. In the whenever block, we use the $.irc attribute provided by the IRC::Client::Plugin role to call method .send on the Client Object. In the :where parameter, we specify we want to send the message to channel #raku and the :text parameter contains the text we want to send. The bot will send that text every 3 seconds.

Up Next

Read the event reference next.