use strict;
use warnings;

    package MyConfig;
    use XML::Simple;
    my $singleton;
    my $XMLfile_name="";
    my @hostList = ();

    sub new {
        my $class = shift;
        #create singleton
        $singleton ||= bless {}, $class;
#Error here: Useless use of hash element in void context
	$singleton->{$XMLfile_name}=$_[0];
	return $singleton;
    }

    sub loadConfig{
    my $self=shift;
    my $xml = XML::Simple->new;
    my $config = $xml->XMLin($file_name, 
ForceArray => [ 'host', 'component' ]) or die$!;

    my $index=0;
    while($config->{host}->{component}->[$index++])
    {
 push @hostList, $config->{host}->{component}->[0]->{component_name};
    }
   }
1;

##</code><code>##

 
<root>
	    <component component_name="n1" />
		<component component_name="n2" />
		<component component_name="n3" />
	</root>
##</code><code>##

use strict;
use MyConfig;
my $CONFIG = "somefile.xml";
&main;
sub main
{
	my configReader = MyConfig->new( $CONFIG );
	configReader->loadConfig;
}