bless do { my %self = (%{Colour->new($colour)}, %{Age->new($age)}); \%self }, $class;

##</code><code>##

package Colour {
    use Scalar::Util 'refaddr';
    my %colour;
    sub new {
        my $o = bless \do{my $var}, $_[0];
        $colour{refaddr $o} = $_[1];
        $o;
    }
    sub colour {$colour{refaddr $_[0]}}
};
package Age {
    use Scalar::Util 'refaddr';
    my %age;
    sub new {
        my $o = bless \do{my $var}, $_[0];
        $age{refaddr $o} = $_[1];
        $o;
    }
    sub age {$age{refaddr $_[0]}}
};
package Colour_and_Age {
    our @ISA = qw[Age Colour];
    use Scalar::Util 'refaddr';
    sub new {
        my ($class, $colour, $age) = @_;
        ... Now what? ...
    }
}

##</code><code>##

use Scalar::Util 'refaddr';
package Colour {
    use Scalar::Util 'refaddr';
    my %colour;
    sub new {bless \do{my $var}, $_[0]}
    sub init {$colour{refaddr $_[0]} = $_[1]; $_[0]}
    sub colour {$colour{refaddr $_[0]}}
};
package Age {
    use Scalar::Util 'refaddr';
    my %age;
    sub new {bless \do{my $var}, $_[0]}
    sub init {$age{refaddr $_[0]} = $_[1]; $_[0]}
    sub age {$age{refaddr $_[0]}}
};

##</code><code>##

package Colour_and_Age {
    use Scalar::Util 'refaddr';
    our @ISA = qw[Age Colour];
    sub new {bless \do{my $var}, $_[0]}
    sub init (
        my ($self, $colour, $age) = @_;
        $self->Colour::init($colour);
        $self->Age::init($age);
        $self;
    }
};

my $o = Colour_and_Age::->new->init(red => 42);