package itemDispatch;

use strict;
use warnings;

# The index to the dispatch hash is an item name, the contents is
#	a list of the callbacks that have been subscribed...
my %DISPATCH;				# Dispatch hash

####################################################################
# Subroutine: Subscribe (external)
#	This routine subscribes a callback function to a dispatch item
# Arguments:
#	$_[0] - Item Name
#	$_[1] - Callback function
####################################################################
sub Subscribe
{
	my $item = shift || die "missing dispatch item";
	my $callback = shift || die "Missing callback function";

	push(@{$DISPATCH{$item}}, $callback);
}

####################################################################
# Subroutine: Activate (external)
#	This routine activates a dispatch item
# Arguments:
#	$_[0] - Item Name
#	$_[1]..$[-1] - Callback args
####################################################################
sub Activate
{
	# Get arguments...
	my $item = shift || die "Missing dispatch item";
	my @args = @_;				# Callback arguments

	my $coderef;
	foreach $coderef (@{$DISPATCH{$item}}) {
		&$coderef(@args);
	}
}

1;

##</code><code>##

package doWork;

use strict;

use Tk;
use itemDispatch;

my $PROGRESS = 0;

sub StartWork {
	my $increment = shift || die "Missing Increment";

	my $c=0;
	while ($c<99) {
		sleep 1;
		itemDispatch::Activate('PROGRESS', $increment);
		$c += $increment;
	}
}

1;

##</code><code>##

use strict;

use Tk;
use Tk::StatusBar;
use itemDispatch;
use doWork;

# Subscribe to PROGRESS events...
itemDispatch::Subscribe('PROGRESS', \&_updateProgress);

my $PROGRESS = 0;
my $INCREMENT = 5;

my $mw = MainWindow->new();

$mw->Button( -text => 'Start', -command => 
	# Publish a START event...
	sub{ doWork::StartWork($INCREMENT)})->pack();

my $sb = $mw->StatusBar();

$sb->addProgressBar(
    -length         =>  60,
    -from           =>   0,
    -to             =>  99,
    -variable       => \$PROGRESS,
);

MainLoop();

sub _updateProgress {
	my $progress = shift || die "Missing Progress\n";
	print STDERR "Updating progress by $progress\n";
	$PROGRESS += $progress;
	$mw->update;
}