Exception::Base subclassing with attributes

exception.pl

use 5.014;
use warnings;

use Try::Tiny;
use Exception::Base (
    'My::Exception' => {
        has => [ qw( usermsg logmsg attr ) ],
        string_attributes => [ qw( usermsg logmsg ) ],
    },
);

try {
        My::Exception->throw(
            value => 1,
            attr    => 'bad',
            logmsg  => 'really obscure and technical',
            usermsg => 'this message is useless'
        );
}
catch {
    warn $_;
    say $_->usermsg;    

    say 'this is really bad' if $_->attr eq 'bad';
}