package SugarMaker;

use Moose ();
use Moose::Exporter;
use Moose::Util;

Moose::Exporter->setup_import_methods(
    with_meta => ['attributes']
);

sub attributes {
    my($meta, %opt) = @_;
    $meta->attributes(\%opt);
}

after import => sub {
    my($class) = @_;
    my $sugar_class = caller();
     Moose::Exporter->setup_import_methods(
         as_is => 'attributes',
         also => 'Moose',
         exporter_package => $sugar_class,
    );
    $sugar_class->add_before_method_modifier(import => sub {
        my($class) = @_;
        my $target_class = caller();
        $target_class->Moose::init_meta(metaclass => 'SugarMaker::Meta::Class');
    });
};

package SugarMaker::Meta::Class;
use Moose;
extends 'Moose::Meta::Class';

has sugar_for_attributes => (isa => 'HashRef', is => 'ro');

before add_attribute => sub {
    my($self, $opt) = @_;
    %$opt = (%$opt, %{$self->sugar_for_attibutes});
};

package Sugar;
use SugarMaker;

attributes is => 'ro';

package UserClass; # final class using sugar
use Sugar;

has 'foo' => (isa => 'Bar'); # implied is => 'ro' from Sugar

package MooseClass; # UserClass is equivalent to this, if done with pure Moose
use Moose;

has foo => (isa => 'Bar', is => 'ro');