There are two different ways of doing it. Let's assume you have a Pet::Dog class and a Pet::Cat class, and you want both animals to be able to jump.

The first technique is to use roles. A role is a unit of functionality that can be imported into several different classes. There are various packages on CPAN for creating roles, but here we'll use Role::Tiny...

#!/usr/bin/env perl

use v5.14;

package Roles::Jumper {
    use Role::Tiny;
    
    # The 'jump' method calls 'name', which means that all
    # classes that consume this role, must provide a 'name'
    # method.
    # 
    requires "name";
    
    # And here's the 'jump' method itself.
    #
    sub jump {
        my $self = shift;
        say $self->name, " jumps!";
    }
}

package Pet::Dog {
    # The Pet::Dog class should consume Roles::Jumper.
    #
    use Role::Tiny::With;
    with "Roles::Jumper";
    
    sub new {
        my $class = shift;
        bless {@_}, $class;
    }
    sub name {
        my $self = shift;
        return $self->{name};
    }
    sub sound {
        my $self = shift;
        say $self->name, " says woof!";
    }
}

package Pet::Cat {
    # The Pet::Cat class should also consume Roles::Jumper.
    #
    use Role::Tiny::With;
    with "Roles::Jumper";
    
    sub new {
        my $class = shift;
        bless {@_}, $class;
    }
    sub name {
        my $self = shift;
        return $self->{name};
    }
    sub sound {
        my $self = shift;
        say $self->name, " says meow!";
    }
}

my $fido  = Pet::Dog->new(name => "Fido");
$fido->jump;
$fido->sound;

my $felix = Pet::Cat->new(name => "Felix");
$felix->jump;
$felix->sound;
[download]

The other technique is to use inheritance from a base class. A Pet::Cat is a Pet::Mammal, isn't it? And so is a Pet::Dog. So we create a Pet::Mammal class and put all our common functionality into there. Then Pet::Cat and Pet::Dog can be simple subclasses of Pet::Mammal.

#!/usr/bin/env perl

use v5.14;

package Pet::Mammal {
    sub new {
        my $class = shift;
        bless {@_}, $class;
    }
    sub name {
        my $self = shift;
        return $self->{name};
    }    
    sub jump {
        my $self = shift;
        say $self->name, " jumps!";
    }
}

package Pet::Dog {
    use base "Pet::Mammal";
    sub sound {
        my $self = shift;
        say $self->name, " says woof!";
    }
}

package Pet::Cat {
    use base "Pet::Mammal";
    sub sound {
        my $self = shift;
        say $self->name, " says meow!";
    }
}

my $fido  = Pet::Dog->new(name => "Fido");
$fido->jump;
$fido->sound;

my $felix = Pet::Cat->new(name => "Felix");
$felix->jump;
$felix->sound;
[download]

So which technique should you use? When there's a clear "is-a" relationship between the classes (a Cat is-a Mammal, a Dog is-a Mammal), and when the base class (Mammal in this case) is potentially useful by itself, then use inheritance. Otherwise, use roles.

Update: I'll also point out that it often makes sense to use both inheritance and roles. For example a "Guard::Dog" class could inherit from "Pet::Dog" and also compose the "Security::Guard" role.

package Security::Guard {
    use Role::Tiny;
    requires "sound";
    sub raise_alarm {
        my $self = shift;
        $self->sound;
    }
}

package Guard::Dog {
    use base "Pet::Dog";
    use Role::Tiny::With;
    with "Security::Guard";
}
[download]

Update II: also note that while I've used syntax from Perl 5.14 in the examples above, this is merely for clarity. Role::Tiny and base each support Perl 5.8, and the examples could be rewritten to run on Perl 5.8 with fairly trivial changes.

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