doc/PERL-HOWTO.dox

/** @page perl-howto Perl Scripting HOWTO

@section Introduction
Gaim Perl Plugins are set up very similarly to their C counterparts.  Most of the API calls are implemented and are divided into packages.  There are some significant differences between the Perl and C API.  Much like the C API, the best place to seek guidance is the source, which is located in the *.xs files in the [libgaim|gtk]/plugins/perl/common directories.  The tutorial that follows will be example based and attempt to touch on some of the notable features of the embedded perl interpreter.  It is also important to note that some of the C API is missing in Gaim's perl API.

It is possible to get Gtk2-Perl to work with Gaim's Perl API, however you must not load the module with @c use, but rather with @c require.  Keep this in mind if you would like to use other perl modules that are dynamically loaded.  You can avoid the problem by always using @c require instead of @c use.

@section first-script Writing your first script

Let us start with a simple example of a Gaim perl plugin.  The following code sample is a complete plugin that can be copied and used as-is.

@code
use Gaim;

%PLUGIN_INFO = (
	perl_api_version => 2,
	name => "Perl Test Plugin",
	version => "0.1",
	summary => "Test plugin for the Perl interpreter.",
	description => "Your description here",
	author => "John H. Kelm <johnhkelm\@gmail.com",
	url => "http://gaim.sourceforge.net/",

	load => "plugin_load",
	unload => "plugin_unload"
);

sub plugin_init {
	return %PLUGIN_INFO;
}

sub plugin_load {
	my $plugin = shift;
	Gaim::Debug::info("testplugin", "plugin_load() - Test Plugin Loaded.\n");
}

sub plugin_unload {
	my $plugin = shift;
	Gaim::Debug::info("testplugin", "plugin_unload() - Test Plugin Unloaded.\n");
}
@endcode

It is necessary to load the libgaim perl package with the @code use Gaim; @endcode line; this makes all the libgaim perl API available to the script.  The @c \%PLUGIN_INFO hash contains all the information that will be displayed in the Plugin frame of the Preferences dialog, it also contains information about how the plugin is to be handled.  The @c load and @c unload keys specify subroutines to be called when the plugin is loaded and unloaded.  There are other key values that may be present in the @c \%PLUGIN_INFO hash; some of those will be covered in the following sections.

The Perl subroutine @c plugin_init is executed when the plugin is probed by the plugin subsystem.  What this means is that as soon as gaim is started, this subroutine is run once, regardless of whether or not the plugin is actually loaded. The other two subroutines present are the @c load and @c unload routines specified in the @c \%PLUGIN_INFO hash and will receive the plugin handle as an argument.  When the plugin is loaded and subsequently unloaded, it will print a message to the debug window using the @c Gaim::Debug::info() Gaim perl API call.

In order to use this simple plugin, save the script text in a file with a @c .pl extension in your ~/.gaim/plugins directory.  After restarting gaim, you should see the plugin  ("Perl Test Plugin") listed in the plugin list under "Tools -> Plugins".  To view the debug output, make sure you run Gaim from the console with the '-d' flag or open the Debug Window which is available in the "Help" menu.  When you check the checkbox next the plugin, you should see a message appear in the Debug Window (or console); similarly, when you uncheck the checkbox you should see another message appear.  You have now created a framework that will allow you to create almost any kind of Gaim plugin you can imagine.

@section account-api Account and Account Option Functions

The Account API is in the @c Gaim::Account:: and @c Gaim::Accounts:: packages;
both are nearly identical to their C counterparts, @c gaim_account_ and @c
gaim_accounts_.  The Account Option API is in the @c Gaim::Account::Option
package and is identical to the C implementation, @c gaim_account_option.

The Account* APIs allow scripts to create, remove, and edit accounts.  An
account will have the Perl type of "GaimAccount". (Note: Gaim types have no real
meaning in perl scripts, other than that the types passed to perl subroutines
need to be correct.)  This section will not go into detail about the @c
Gaim::Account::Option package since its use is mainly in building protocol
plugins, which are outside the scope of this document.  However, the API for the
@c Gaim::Account::Option package should function as expected, should you need to
use it.

To reduce redundant code, the following code examples will use the simple plugin
from the previous section as a template.  To highlight some of the more useful
features of the Account API, we will be replacing the @c plugin_load perl
subroutine.  For testing purposes, we will display output on the command line by
using perl @c print commands.

@code
sub plugin_load {
	$plugin = shift;

	# Testing was done using Oscar, but this should work regardless of the protocol chosen
	my $protocol = "prpl-oscar";
	my $account_name = "test";

	# Create a new Account
	print "Testing: Gaim::Account::new()... ";
	$account = Gaim::Account->new($account_name, $protocol);
	if ($account) { print "ok.\n"; } else { print "fail.\n"; }

	# Add a new Account
	print "Testing: Gaim::Account::add()...";
	Gaim::Accounts::add($account);
	print "pending find...\n";

	# Find the account we just added to verify its existence
	print "Testing: Gaim::Accounts::find()...";
	$account = Gaim::Accounts::find($account_name, $protocol);
	if ($account) { print "ok.\n"; } else { print "fail.\n"; }

	# Return the username
	print "Testing: Gaim::Account::get_username()... ";
	$user_name = $account->get_username();
	if ($user_name) {
		print "Success: $user_name.\n";
	} else {
		print "Failed!\n";
	}
	# Verify if the user is connected
	print "Testing: Gaim::Account::is_connected()";
	if ($account->is_connected()) {
		print " Connected.\n";
	} else {
		print " Disconnected.\n";
	}

	# The status mechanism is how users are Connected, set Away,
	# Disconnected (status set to Offline), etc
	#  $status is now a Gaim::Status perl type.
	print "Testing: Gaim::Accounts::get_active_status()... ";
	if ($account->get_active_status()) {
		print "Okay.\n";
	} else {
		print "Failed!\n";
	}

	# It follows that to connect a user you must set the account status to
	# "available" similarly we can disconnect a user by setting the account
	# status to "offline"

	print "Testing: Gaim::Accounts::connect()...pending...\n";

	$account->set_status("available", TRUE);
	$account->set_enabled(Gaim::Core::get_ui(), TRUE);
	$account->connect();

}
@endcode

The above code is mostly explained in the comments, however there are a few
notable points to make.  The variables above are all specialized Perl types that
contain pointers to the actual Gaim types.  They can be reassigned at will, just
like any other variable in Perl.  The only way to edit the internal values of a
Gaim type from within perl is to use the accessor methods, e.g.
@c Gaim::Account::get_username().  If you would like to assign a C @c NULL value,
simply use @c undef.

@section buddylist-api Buddylist, Group and Chat API

The BuddyList, Group and Chat APIs are very similar and whatever is shown for
the @c Gaim::BuddyList API should carry over to @c Gaim::BuddyList::Chat and
@c Gaim::BuddyList::Group.  Note that a @c Gaim::Find package was created to
keep the naming consistent with the C API.

@code
sub plugin_load {
	my $plugin = shift;

	my $protocol = "prpl-oscar";
	my $account_name = "test";

	# This is how we get an account to use in the following tests.  You should replace the username
	#  with an existing user
	$account = Gaim::Accounts::find($account_name, $protocol);

	# Testing a find function: Note Gaim::Find not Gaim::Buddy:find!
	#  Furthermore, this should work the same for chats and groups
	Gaim::Debug::info("testplugin", "Testing: Gaim::Find::buddy()...");
	$buddy = Gaim::Find::buddy($account, "BUDDYNAME");
	Gaim::Debug::info("", ($buddy ? "ok." : "fail.") . "\n");

	# If you should need the handle for some reason, here is how you do it
	Gaim::Debug::info("testplugin", "Testing: Gaim::BuddyList::get_handle()...");
	$handle = Gaim::BuddyList::get_handle();
	Gaim::Debug::info("", ($handle ? "ok." : "fail.") . "\n");

	# This gets the Gaim::BuddyList and references it by $blist
	Gaim::Debug::info("testplugin", "Testing: Gaim::get_blist()...");
	$blist = Gaim::get_blist();
	Gaim::Debug::info("", ($blist ? "ok." : "fail.") . "\n");

	# This is how you would add a buddy named "NEWNAME" with the alias "ALIAS"
	Gaim::Debug::info("testplugin", "Testing: Gaim::BuddyList::Buddy::new...");
	$buddy = Gaim::BuddyList::Buddy::new($account, "NEWNAME", "ALIAS");
	Gaim::Debug::info("", ($buddy ? "ok." : "fail.") . "\n");

	# Here we add the new buddy '$buddy' to the group "GROUP"
	#  so first we must find the group
	Gaim::Debug::info("testplugin", "Testing: Gaim::Find::group...");
	$group = Gaim::Find::group("GROUP");
	Gaim::Debug::info("", ($group ? "ok." : "fail.") . "\n");

	# To add the buddy we need to have the buddy, contact, group and node for insertion.
	#  For this example we can let contact be undef and set the insertion node as the group
	Gaim::Debug::info("testplugin", "Testing: Gaim::BuddyList::add_buddy...\n");
	Gaim::BuddyList::add_buddy($buddy, undef, $group, $group);

	# The example that follows gives an indication of how an API call that returns a list is handled.
	#  In this case the buddies of the account found earlier are retrieved and put in an array '@buddy_array'
	#  Further down an accessor method is used, 'get_name()' -- see source for details on the full set of methods
	Gaim::Debug::info("testplugin",  "Testing: Gaim::Find::buddies...\n");
	@buddy_array = Gaim::Find::buddies($account, undef);
	if (@buddy_array) {
		Gaim::Debug::info("testplugin", "Buddies in list (" . @buddy_array . "): \n");
		foreach $bud (@buddy_array) {
			Gaim::Debug::info("testplugin", Gaim::BuddyList::Buddy::get_name($bud) . "\n");
		}
	}
}
@endcode

The BuddyList API allows plugins to edit buddies in the list, find the buddies
for a given account, assign aliases, and further manipulate the structure
as needed.  It is also contains methods for accessing @c Gaim::BuddyList::Group
and @c Gaim::BuddyList::Chat types.

@section conn-api Connection API

The @c Gaim::Connection API is one of the many packages that will not be covered
in-depth in this tutorial.  It is most useful to protocol plugin developers.
However, the entire @c gaim_connection_ API has corresponding, functioning perl subroutines.

@section conv-api Conversation API

The Gaim perl APIs for @c gaim_conversation_ and @c gaim_conv_window_ allow
plugins to interact with existing conversations, create new conversations, and
modify conversations at will.  In the example script, a new window is created,
displayed and a new conversation instant message is created.  The following
example again replaces the @c plugin_load subroutine in the simple plugin
template.  The @c Gaim::Conversation::Chat package handles the
@c gaim_conv_chat_ portion of the API very similarly to how the
Gaim::Conversation::IM package is used in the examples that follow.

Notice that the interaction with the conversation window is in the @c Gaim::GtkUI package as it
is UI-specific code interacting with gtkgaim and not libgaim.
To use any of the Gaim::GtkUI functionality, you will need to add the following to the top of your script: @code use Gaim::GtkUI; @endcode


@code
sub plugin_load {
	my $plugin = shift;
	my $protocol = "prpl-oscar";
	my $account_name = "test";

	$account = Gaim::Accounts::find($account_name, $protocol);

	# First we create two new conversations.
	print "Testing Gaim::Conversation->new()...";
	$conv1 = Gaim::Conversation->new(1, $account, "Test Conversation 1");
	if ($conv1) { print "ok.\n"; } else { print "fail.\n"; }

	print "Testing Gaim::Conversation->new()...";
	$conv2 = Gaim::Conversation->new(1, $account, "Test Conversation 2");
	if ($conv2) { print "ok.\n"; } else { print "fail.\n"; }
	
	# Second we create a window to display the conversations in.
	#  Note that the package here is Gaim::GtkUI::Conversation::Window
	print "Testing Gaim::GtkUI::Conversation::Window->new()...\n";
	$win = Gaim::GtkUI::Conversation::Window->new();

	# The third thing to do is to move second the conversation to a new window.
	# The subroutine add_gtkconv() returns the number of conversations
	# present in the window.
	print "Testing Gaim::GtkUI::Conversation::Window::add_conversation()...";
	$gtkconv2 = Gaim::GtkUI::Conversation::get_gtkconv($conv2);
	$gtkconv2->get_window()->remove_gtkconv($gtkconv2);
	$conv_count = $win->add_gtkconv($gtkconv2);
	if ($conv_count) {
		print "ok..." . $conv_count . " conversations...\n";
	} else {
		print "fail.\n";
	}

	# Now the window is displayed to the user.
	print "Testing Gaim::GtkUI::Conversation::Window::show()...\n";
	$win->show();

	# Use get_im_data() to get a handle for the conversation
	print "Testing Gaim::Conversation::get_im_data()...\n";
	$im = $conv1->get_im_data();
	if ($im) { print "ok.\n"; } else { print "fail.\n"; }

	# Here we send messages to the conversation
	print "Testing Gaim::Conversation::IM::send()...\n";
	$im->send("Message Test.");

	print "Testing Gaim::Conversation::IM::write()...\n";
	$conv2->get_im_data()->write("SENDER", "<b>Message</b> Test.", 0, 0);
}
@endcode

The next block of code shows how a script can close a known conversation window
@c $win.

@code
	print "Testing Gaim::GtkUI::Conversation::Window::get_gtkconv_count()...\n";
	$conv_count = $win->get_gtkconv_count();
	print "...and it returned $conv_count.\n";
	if ($conv_count > 0) {
		print "Testing Gaim::GtkUI::Conversation::Window::destroy()...\n";
		$win->destroy();
	}
@endcode

@section plugin-pref-api Plugin Preference and Gtk Preference API

The plugin preference API allows plugins to display options for manipulating the
plugin's behavior in a popup window.  The method used for creating the pane in
native C plugins does not allow a direct mapping into perl. Therefore, perl
plugin writers must be aware that there will be significant differences in how
they create plugin preference panes.

To first create a standard plugin preference tab, we need specify the
@c prefs_info key/value pair in the @c \%PLUGIN_INFO hash.  This specifies the
name of the perl subroutine that will build and return a @c Gaim::Pref::Frame.

@code
%PLUGIN_INFO = {
	...,
	prefs_info => "prefs_info_cb"
};
@endcode

The perl subroutine @c prefs_info_cb will be called to create the preferences
popup for the perl plugin.  The following example will demonstrate creating a
preference frame. It is necessary to first initialize the preferences to be used
in the @c plugin_load subroutine, as follows.

@code
sub plugin_load {
	my $plugin = shift;

	# Here we are adding a set of preferences
	#  The second argument is the default value for the preference.
	Gaim::Prefs::add_none("/plugins/core/perl_test");
	Gaim::Prefs::add_bool("/plugins/core/perl_test/bool", 1);
	Gaim::Prefs::add_string("/plugins/core/perl_test/choice_str", "ch1");
	Gaim::Prefs::add_int("/plugins/core/perl_test/choice_int", 1);
	Gaim::Prefs::add_string("/plugins/core/perl_test/text", "Foobar");
}
@endcode

Now we can provide an UI for manipulating these preferences in our @c prefs_info
function.

@code
sub prefs_info_cb {
	# The first step is to initialize the Gaim::Pref::Frame that will be returned
	$frame = Gaim::PluginPref::Frame->new();

	# Create a new boolean option with a label "Boolean Label" and then add
	# it to the frame
	$ppref = Gaim::PluginPref->new_with_label("Boolean Label");
	$frame->add($ppref);

	$ppref = Gaim::PluginPref->new_with_name_and_label(
		"/plugins/core/perl_test/bool", "Boolean Preference");
	$frame->add($ppref);

	# Create a set of choices.  To do so, we must set the type to 1 which is
	# the numerical equivalent of the GaimPrefType for choice.
	$ppref = Gaim::PluginPref->new_with_name_and_label(
		"/plugins/core/perl_test/choice_str", "Choice Preference");
	$ppref->set_type(1);
	$ppref->add_choice("ch0", "ch0");
	# The following will be the default value as set from plugin_load
	$ppref->add_choice("ch1", "ch1");
	$frame->add($ppref);

	# Create a set of choices.  To do so we must set the type to 1 which is
	# the numerical equivalent of the GaimPrefType for choice.
	$ppref = Gaim::PluginPref->new_with_name_and_label(
		"/plugins/core/perl_test/choice_int", "Choice Preference 2");
	$ppref->set_type(1);
	$ppref->add_choice("zero", 0);
	# The following will be the default value as set from plugin_load
	$ppref->add_choice("one", 1);
	$frame->add($ppref);


	# Create a text box.  The default value will be "Foobar" as set by
	# plugin_load
	$ppref = Gaim::PluginPref->new_with_name_and_label(
		"/plugins/core/perl_test/text", "Text Box Preference");
	$ppref->set_type(2);
	$ppref->set_max_length(16);
	$frame->add($ppref);

	return $frame;
}
@endcode

<!--
Using the Gtk2-Perl module for Perl it is possible to create tailored @c GtkFrame elements and display them in a preference window.  Note that Gtk2-Perl must be loaded with @c require and not @c use .  The first step is to create the proper key/value pairs in the @c \%PLUGIN_INFO hash noting that the @c prefs_info key is no longer valid. Instead the keys @c GTK_UI and @c gtk_prefs_info must be set as follows.

@code
%PLUGIN_INFO = {
	...,
	# Used to differentiate between a regular and a Gtk preference frame
	GTK_UI => TRUE,
	gtk_prefs_info => "gtk_prefs_info_cb",
}
@endcode

To finish this example @c gtk_prefs_info_cb needs to be defined.  To introduce some of the flexibility of using Gtk2-Perl the example also includes a button and a callback for the button.  Explaining Gtk2-Perl is beyond the scope of this tutorial and more info can be found at the project's website <a href="http://gtk2-perl.sourceforge.net/">http://gtk2-perl.sourceforge.net/</a>.

@code
# A simple call back that prints out whatever value it is given as an argument.
sub button_cb {
	my $widget = shift;
	my $data = shift;
	print "Clicked button with message: " . $data . "\n";
}

sub gtk_prefs_info_cb {
	#  Create a button that prints a message to the console and places it in the frame.
	use Glib;
	require Gtk2;

	$frame = Gtk2::Frame->new(\'Gtk Test Frame\');
	$button = Gtk2::Button->new(\'Print Message\');

	$frame->set_border_width(10);
	$button->set_border_width(150);
	$button->signal_connect("clicked" => \&button_cb, "Message Text");
	$frame->add($button);

	$button->show();
	$frame->show();

	return $frame;
}
@endcode
-->

@section request-api Request Dialog Box API

The @c Gaim::Request package allows plugins to have interactive dialog boxes
without the need to directly interact with the UI (e.g. GTK+).  This allows core
(libgaim) plugins to create a UI that can be displayed on whichever UI frontend
is being used.  The portion of the Request API available to perl scripts is
listed below, followed by an example illustrating its use.

These arguments are the same for each of the three request types:
	@arg @em handle 	- The plugin handle.
	@arg @em title 		- String title for the dialog.
	@arg @em primary 	- The first sub-heading.
	@arg @em secondary 	- The second sub-heading.
	@arg @em ok_text 	- The Text for the OK button.
	@arg @em ok_cb 		- The string name of the perl subroutine to call when the OK button is clicked.
	@arg @em cancel_text 	- The text for the Cancel button.
	@arg @em cancel_cb 	- The string name of the perl subroutine to call when the Cancel button is clicked.
	@arg @em default_value 	- Default text string to display in the input box.
	@arg @em multiline 	- Boolean where true indicates multiple line input boxes are allowed.
	@arg @em masked 	- Boolean indicating if the user can edit the text.
	@arg @em hint 	- See source for more information - can be left blank.
	@arg @em filename 	- String default file name value.
	@arg @em savedialog 	- Boolean where true indicates use as a save file dialog and false indicates an open file dialog.

@code
# Create a simple text input box
Gaim::Request::input(handle, title, primary, secondary, default_value, multiline, masked, hint, ok_text, ok_cb, cancel_text, cancel_cb);

# Prompt user to select a file
Gaim::Request::file(handle, title, filename, savedialog, ok_cb, cancel_cb);

# Create a unique input dialog as shown in the following example
Gaim::Request::fields(handle, title, primary, secondary, fields, ok_text, ok_cb, cancel_text, cancel_cb);
@endcode

The following is an example of a @c Gaim::Request::fields() dialog box with a
callback for the OK button and another for the Cancel Button.

@code
sub ok_cb_test{
	# The $fields is passed to the callback function when the button is clicked.
	# To access a specific field, it must be extracted from $fields by name.
	$fields = shift;
	$account = Gaim::Request::Fields::get_account($fields, "acct_test");
	$int = Gaim::Request::Fields::get_integer($fields, "int_test");
	$choice = Gaim::Request::Fields::get_choice($fields, "ch_test");
}

sub cancel_cb_test{
	# Cancel does nothing but is equivalent to the ok_cb_test
}

sub plugin_load {
	my $plugin = shift;

	# Create a group to pool together multiple fields.
	$group = Gaim::Request::Field::Group::new("Group Name");

	# Each field is created with Gaim::Request::*_new(), is made viewable with Gaim::Request::field_*_set_show_all()
	#  and is then added to the group with Gaim::Request::field_group_add_field()

	# Add an account combobox containing all active accounts
	$field = Gaim::Request::Field::account_new("acct_test", "Account Text", undef);
	Gaim::Request::Field::account_set_show_all($field, 0);
	Gaim::Request::Field::Group::add_field($group, $field);

	# Add an integer input box
	$field = Gaim::Request::Field::int_new("int_test", "Integer Text", 33);
	Gaim::Request::Field::Group::add_field($group, $field);

	# Add a list of choices
	$field = Gaim::Request::Field::choice_new("ch_test", "Choice Text", 1);
	Gaim::Request::Field::choice_add($field, "Choice 0");
	Gaim::Request::Field::choice_add($field, "Choice 1");
	Gaim::Request::Field::choice_add($field, "Choice 2");

	Gaim::Request::Field::Group::add_field($group, $field);

	# Create a Gaim::Request and add the group that was just created.
	$request = Gaim::Request::Fields::new();
	Gaim::Request::Fields::add_group($request, $group);

	#  Display the dialog box with the input fields added earlier with the appropriate titles.
	Gaim::Request::fields(
		$plugin,
		"Request Title!",
		"Primary Title",
		"Secondary Title",
		$request,
		"Ok Text", "ok_cb_test",
		"Cancel Text", "cancel_cb_test");
}
@endcode

@section timeout-cb Misc: Plugin Actions, Timeouts and Callbacks

This section of the manual covers some of the important features that can be
added to Gaim perl Plugins.  Plugin actions are callback functions that are
accessible to the user from the Buddy List window under "Tools -> [Plugin Name]".
Timeouts allow a plugin to execute a perl subroutine after a given period of time.
Note that timeouts only occur once, so if the timeout must occur periodically,
the timeout needs to be re-added at the end of the timeout callback function.
Callbacks are functions that are called when an event occurs (such as a buddy
signing-on, or a message being received).  The following three examples will
demonstrate the usage of these features.

Plugin actions require the @c \%PLUGIN_INFO hash to have a key/value pair added,
specifying a perl subroutine which will list the available actions; each action
listed must have a definition, including a reference to a callback subroutine,
added to the @c \%plugin_actions hash.

@code
%PLUGIN_INFO = {
	...,
	plugin_action_sub => "plugin_actions_cb",
}

sub plugin_actions_cb {
	my @actions = ("Action 1", "Action 2");
}

%plugin_actions = (
	# The callback subroutine that is called when "Tools -> Plugin -> Action 1" is selected
	"Action 1" => \&action1_cb,
	# The callback subroutine that is called when "Tools -> Plugin -> Action 2" is selected
	"Action 2" => \&action2_cb
);

sub action1_cb {
	Gaim::Debug::info("Test Plugin", "Action 1 activated\n");
}

sub action2_cb {
	Gaim::Debug::info("Test Plugin", "Action 2 activated\n");
}
@endcode

Timeouts allow a perl subroutine to be executed after a specified time.  They only occur once, so, as stated earlier, the timeout must be re-registered after every time it is called.

@code
sub timeout_cb {
	my $plugin = shift;
	Gaim::Debug::info("testplugin", "Timeout occurred.\n");

	# Reschedule timeout
	Gaim::timeout_add($plugin, 10, \&timeout_cb, $plugin);
}

sub plugin_load {
	$plugin = shift;

	# Schedule a timeout for ten seconds from now
	Gaim::timeout_add($plugin, 10, \&timeout_cb, $plugin);
}
@endcode

Callbacks are handled by creating a perl subroutine to serve as the callback and
then attaching the callback to a signal.

@code
sub signal_cb {
	# The signal data and the user data come in as arguments
	my ($account, $data) = @_;
	Gaim::Debug::info("testplugin", "Account \"" . $account->get_username() . "\" just connected.\n");
}

sub plugin_load {
	$plugin = shift;

	# User data to be given as an argument to the callback perl subroutine.
	$data = "";

	# A pointer to the handle to which the signal belongs needed by the callback function
	$accounts_handle = Gaim::Accounts::get_handle();

	# Connect the perl subroutine 'signal_cb' to the event 'account-connecting'
	Gaim::Signal::connect($accounts_handle, "account-connecting", $plugin, \&signal_cb, $data);
}
@endcode

@section Resources
	@see API Documentation

*/