gistfile1.pl

package Location;

sub new {
    my ($class, %args) = @_;
    my $subclass = "Location::$args{location_type}";
    return bless \%args, $subclass;
}

package Location::Country;

use base 'Location';

sub new {
    my ($class, %args) = @_;
    my $self = Location->new(%args);

    # do something Country-specific

    return $self;
}

sub description { "a country called $_[0]{name}" }

package Location::City;

use base 'Location';

sub new {
    my ($class, %args) = @_;
    my $self = Location->new(%args);

    # do something City-specific

    return $self;
}

sub description { "a city called $_[0]{name}" }

package main;

# any users of Location->new will get back an object that isa("Location")
# which might or might not be an instance of a derivative class

my $country = Location->new(
    type => 'country',
    name => 'Foo',
);

my $country = Location->new(
    type => 'city',
    name => 'Bar',
);