# -*- Perl -*-

use strict;
use warnings;

package Matrix::Named;

use Scalar::Util qw/refaddr/;

use base 'Matrix';

{
    my %name;
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Say I've picked up your nifty Matrix class from somewhere, and this this lovely Angle class from somewhere else. I want to combine them in a class MyAngle so that matrix operations can be applied to an angle and refer to the corresponding rotational matrix.

Unfortunately, Angle is implemented in the traditional way as a (scalar) ref to the numeric value.

package Angle;
use strict; use warnings;

use constant PI => 4*atan2( 1, 1);
use constant RAD => 180/PI;

sub cre { bless \ my $angle, shift }
sub new {
    my $class = shift;
    $class->Angle::cre->Angle::init( @_);
}

sub init {
    my $obj = shift;
    $$obj = _get_angle( @_);
    $obj;
}

sub rad { ${ shift() } };
sub deg { ${ shift() }*RAD }

sub _get_angle {
    my $angle;
    if ( @_ == 1 ) {
        $angle = shift;
    } else {
        my %spec = @_;
        $angle = exists $spec{ deg} ?  $spec{ deg}/RAD : $spec{ rad};
    }
    modulo( $angle, 2*PI);
}

use POSIX;
sub modulo {
    my ( $x, $y) = @_;
    $y ? $x - $y*POSIX::floor( $x/$y) : $x;
}

1;
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#!/usr/local/bin/perl
use strict; use warnings; $| = 1;
use Vi::QuickFix;

# Definition of MyAngle below

my $alpha = MyAngle->new( rad => atan2( 1, 1));
printf "Angle: %s (%s deg)\n", $alpha->rad, $alpha->deg;  # Angle func
+tions
print "Matrix:\n$alpha\n"; # show the matrix representation

##################################################

package MyAngle;
use lib 'lib';
use base 'Angle';
use base 'Matrix';

sub new {
    my $class = shift;
    $class->Angle::cre->MyAngle::init( @_);
}

sub init {
    my $obj = shift;
    $obj->Angle::init( @_);
    $obj->Matrix::init( cos( $_), -sin( $_), sin( $_), cos( $_)) for
        $obj->rad;
    $obj;
}

__END__
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Anno

PS: If you actually want to run the code against the inside-out implementation of Matrix use the updated code from my previous posting. There was a bug in the original that would have been a show-stopper.