use warnings;
use strict;

package Factory {
	sub new {
		my ($class,%args) = @_;
		my $self = {
				config => _read_config( $args{config_file} ),
			};
		return bless $self, $class;
	}
	sub _read_config {
		my $file = shift;
		my %config;
		# ...
		return \%config;
	}
	sub make_object_from_data {
		my ($self,$data) = @_;
		my %args;
		# complex code to build %args from $data using $self->{config}
		return Object->new(%args);
	}
}

package Object {
	sub new {
		my ($class,%args) = @_;
		my $self = \%args;
		return bless $self, $class;
	}
	# ...
}

my $factory = Factory->new( config_file => "file.xml" );
my $obj1 = $factory->make_object_from_data( { foo=>123 } );
my $obj2 = $factory->make_object_from_data( { bar=>456 } );

##</code><code>##

use warnings;
use strict;

package Config {
	sub new {
		my ($class,%args) = @_;
		my $self = {};
		# code to read $args{config_file} into $self
		return bless $self, $class;
	}
}

package Object {
	sub new {
		my ($class,%args) = @_;
		my $self = _parse_data_with_config($args{config},$args{data});
		return bless $self, $class;
	}
	sub _parse_data_with_config {
		my ($config, $data) = @_;
		my $self = {};
		# complex code to build $self from $data using $config
		return $self;
	}
	# ...
}

my $config = Config->new( config_file => "file.xml" );
my $obj1 = Object->new( config => $config, data => { foo=>123 } );
my $obj2 = Object->new( config => $config, data => { bar=>456 } );

##</code><code>##

	sub new_object {
		my ($self,$data) = @_;
		return Object->new( config=>$self, data=>$data );
	}

# ... call as:
my $obj3 = $config->new_object( { quz=>789 } );