package pm_moose_default_params;

use Moose;

has colour => (
    is       => 'rw',
    isa      => 'Str',
    required => 0,
    lazy     => 1,
    default  => 'red',
);

has shape => (
    is       => 'rw',
    isa      => 'Str',
    required => 0,
    lazy     => 1,
    default  => 'circle',
);

no Moose;
__PACKAGE__->meta->make_immutable;

##</code><code>##

#!/usr/bin/env perl

use 5.010;
use strict;
use warnings;

use Getopt::Long;

use pm_moose_default_params;

my $colour = '';
my $shape = '';

GetOptions('colour=s' => \$colour, 'shape=s' => \$shape);

say "Option --colour = $colour";
say "Option --shape = $shape";

my %param;
$param{colour} = $colour if $colour;
$param{shape} = $shape if $shape;

say "Param $_ = $param{$_}" for keys %param;

my $object = pm_moose_default_params::->new(%param);

say 'Moose colour = ', $object->colour;
say 'Moose shape = ', $object->shape;

##</code><code>##

$ pm_moose_default_params.pl
Option --colour = 
Option --shape = 
Moose colour = red
Moose shape = circle

$ pm_moose_default_params.pl --colour=blue
Option --colour = blue
Option --shape = 
Param colour = blue
Moose colour = blue
Moose shape = circle

$ pm_moose_default_params.pl --shape=square
Option --colour = 
Option --shape = square
Param shape = square
Moose colour = red
Moose shape = square

$ pm_moose_default_params.pl --colour=blue --shape=square
Option --colour = blue
Option --shape = square
Param colour = blue
Param shape = square
Moose colour = blue
Moose shape = square