Class Attributes in roles?

Code like this:

---------------------------------------------------------------------
#!/usr/bin/env perl

{
    package RoleFoo;
    use Moose::Role;
    use MooseX::ClassAttribute;

    class_has 'fooAttr' => ( is => 'rw' );   # this doesn't.
}
{
    package ClassBar;
    use Moose;
    with 'RoleFoo';

    has 'barAttr' => ( is => 'rw' );
}

my $bar = ClassBar->new(barAttr => 'dummy');
print "barAttr: ", $bar->barAttr, "\n";
---------------------------------------------------------------------

Gives this error:

"Can't locate object method "superclasses" via package "Moose::Meta::Role"
at /home/brb/localperl/lib/site_perl/5.10.0/MooseX/ClassAttribute.pm line
32."

I think it would be useful if class attributes could be declared in roles in
the same way they are declared in classes.

Bernardo