package myclass;
use Carp qw(croak);

sub new {
    my ($class, $value) = @_;

    croak "required value missing" if @_ == 1 or !$value;

    return bless \$value, $class;
}

package mysubclass;
use base qw(myclass);

sub new {
    my ($class) = @_;

    return bless $class->SUPER::new(23), $class;
}

##</code><code>##

package myclass;
use Class::Std;
my %value :ATTR( :init_arg<value> );

package mysubclass;
use base qw(myclass);

sub BUILD {
    my ($self, $ident, $args) = @_;
    $args->{value} = 23;
}

##</code><code>##

mysubclass->new;

##</code><code>##

Missing initializer label for myclass: 'value'.
Fatal error in constructor call