This more or less does what you want...
use strict;
use warnings;
{
package My::Legacy::MyMooseObj;
use Moose;
use MooseX::FunkyAttributes;
use namespace::autoclean;
has _fields => (
isa => 'HashRef',
is => 'rw',
default => sub { {} },
lazy => 1, # you want this, for the rest to work
);
has attr_a => (
isa => 'Int',
is => 'ro',
traits => [ FunkyAttribute ],
custom_get => sub { $_->_fields->{attr_a} },
custom_set => sub { $_->_fields->{attr_a} = $_[-1] },
custom_has => sub { exists($_->_fields->{attr_a}) },
);
has attr_b => (
isa => 'Str',
is => 'rw',
traits => [ FunkyAttribute ],
custom_get => sub { $_->_fields->{attr_b} },
custom_set => sub { $_->_fields->{attr_b} = $_[-1] },
custom_has => sub { exists($_->_fields->{attr_b}) },
);
}
my $obj = My::Legacy::MyMooseObj->new( attr_a => 42 );
$obj->attr_b(666);
print $obj->dump;
With the current version of MooseX::FunkyAttributes, the constructor will not work correctly if you do the whole __PACKAGE__->meta->make_immutable
though. :-(
Delving slightly deeper into metaprogramming...
use strict;
use warnings;
{
package My::Legacy::MyMooseObj;
use Moose;
use MooseX::FunkyAttributes;
use namespace::autoclean;
has _fields => (
isa => 'HashRef',
is => 'rw',
default => sub { {} },
lazy => 1, # you want this, for the rest to work
);
sub funky_has {
my ($attr, %opts) = @_;
has $attr => (
is => 'ro',
traits => [ FunkyAttribute ],
custom_get => sub { $_->_fields->{$attr} },
custom_set => sub { $_->_fields->{$attr} = $_[-1] },
custom_has => sub { exists($_->_fields->{$attr}) },
%opts,
);
}
funky_has attr_a => (isa => 'Int');
funky_has attr_b => (isa => 'Str', is => 'rw');
}
my $obj = My::Legacy::MyMooseObj->new( attr_a => 42 );
$obj->attr_b(666);
print $obj->dump;