About namespaces and inheritance:
Namespaces, like "Animal::Dog", are just names, as was written before. Inheritance is defined differently, but it is good habit to create namespaces related with inheritance, for instance:
package Animal; #parent class, in file lib/Animal.pm
sub new {
return bless {}, shift;
}
sub sound {
die "cannot call this method on class '".ref(shift)."'";
}
sub output_sound {
my ($self, $what) = @_;
print $what."\n";
}
1;
package Animal::Dog; #desc. of Animal, lib/Animal/Dog.pm
use base 'Animal';
sub sound {
my ($self) = @_;
$self->output_sound("haf");
}
1;
package Animal::Dog::Sheepdog; #desc. of Dog
#lib/Animal/Dog/Sheepdog.pm
use base 'Animal::Dog';
sub guard {
my ($self, $flock) = @_;
#do something
}
1;
package Animal::Pig; #other descendant
use base 'Animal';
sub sound {
my ($self) = @_;
$self->output_sound("khro");
}
1;
Now you can create some instance of animal :>) by this way:
use Animal::Dog::Sheepdog;
my $helper = Animal::Dog::Sheepdog->new();
#Once you have an instance, you can call it's methods by this way:
$helper->sound;
Do not hesitate to ask some questions, I had been confused in the same manner. Just note: that code is not tested, it really should have strictings in every module...