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Writing plugins for PyLink
PyLink plugins are modules that extend its functionality by giving it something to do. Without any plugins loaded, PyLink can only sit on a server and do absolutely nothing.
This guide, along with the sample plugin plugin_example.py, aim to show
the basics of writing plugins for PyLink.
Receiving data from IRC
Plugins have three main ways of communicating with IRC: hooks, WHOIS handlers, and commands sent in PM to the main PyLink client. A simple plugin can use one, or any mixture of these.
Hooks
Hooks are probably the most versatile form of communication. The data
in each hook payload is formatted as a Python dict, with
different data keys depending on the command. For example, a
PRIVMSG payload would give you the fields
target and text, while a PART
payload would only give you channels and
reason fields.
There are many hook types available (one for each supported IRC command), and you can read more about them in the PyLink hooks reference.
Plugins can bind to hooks using the utils.add_hook()
function like so: utils.add_hook(function_name, 'PRIVMSG'),
where function_name is your function definition, and
PRIVMSG is whatever hook name you want to bind to. Once set
up, function_name will be called whenever the protocol
module receives a PRIVMSG command.
Each hook-bound function takes 4 arguments:
irc, source, command, args. - irc: The IRC
object where the hook was called. Plugins are globally loaded, so there
will be one of these per network. - source: The numeric
of the sender. This will usually be a UID (for users) or a SID (for
server). - command: The true command name where the
hook originates. This may or may not be the same as the name of the
hook, depending on context. - args: The hook data (a
dict) associated with the command. Again, the available
data keys differ by hook name (see the hooks reference for a list of which can be
used).
Hook functions do not return anything, and can raise exceptions to be caught by the core.
PyLink commands
For plugins that interact with IRC users, there is also the option of binding to PM commands.
Commands are bound to using the utils.add_cmd()
function: utils.add_cmd(testcommand, "hello"). Here,
testcommand is the name of your function, and
hello is the (optional) name of the command to bind to; if
it is not specified, it’ll use the same name as the function. Now, your
command function will be called whenever someone PMs the PyLink client
with the command (e.g. /msg PyLink hello,
case-insensitive).
Each command function takes 3 arguments:
irc, source, args. - irc: The IRC object
where the command was called. - source: The numeric of
the sender. This will usually be a UID (for users) or a SID (for
server). - args: A list of space-separated
command args (excluding the command name) that the command was called
with. For example, /msg PyLink hello world 1234 would give
an args list of ['world', '1234']
Command handlers do not return anything and can raise exceptions, which are caught by the core and automatically return an error message.
WHOIS handlers
The third option, WHOIS handlers, are a lot more limited
compared to the other options. They are solely used for
WHOIS replies, and only work on IRCds where WHOIS
commands are sent to remote servers! This includes Charybdis
and UnrealIRCd, but not InspIRCd, which handles all
WHOIS requests locally (the only thing sent between servers
is an IDLE time query).
WHOIS replies are special in that any plugins wishing to add lines to a WHOIS reply must do so after the regular WHOIS lines (handled by the core), but before a special “End of WHOIS” line. This means that the regular hooks mechanism, which are only called after core handling, doesn’t work here.
An example of a plugin WHOIS handler is in the relay plugin (search for
relayWhoisHandler. WHOIS handler functions are added to the
world.whois_handlers list using a simple
append(). They should return either nothing or a list of
two-length tuples: the first item being the WHOIS numeric, and the
second the raw whois text.
Sending data to IRC
Plugins receive data from the underlying protocol module, and communicate back using outgoing command functions implemented by the protocol module. They should never send raw data directly back to IRC, because that wouldn’t be portable across different IRCds.
These functions are usually called in this fashion:
irc.proto.abcdClient(arg1, arg2). For example, the command
irc.proto.join('10XAAAAAB', '#bots') would join a PyLink
client with UID 10XAAAAAB to channel
#bots.
For sending messages (e.g. replies to commands), simpler forms of:
irc.reply(text, notice=False, source=None)- and
irc.msg(targetUID, text, notice=False, source=None)
are also used.
irc.reply() is a special form of irc.msg in
that it automatically finds the target to reply to. If the command was
called in a channel using fantasy, it will send the reply in that
channel. Otherwise, the reply will be sent in a PM to the caller.
The sender UID for both can be set using the source
argument, and defaults to the main PyLink client.