#!/usr/bin/perl
use warnings;
use strict;

{   package Array::Nonempty::Attr;
    use Attribute::Handlers;

    sub Nonempty :ATTR(ARRAY) {
        tie @{ $_[2] }, 'Array::Nonempty'
    }

}


{   package Array::Nonempty;
    use Tie::Array;
    use parent -norequire => 'Tie::StdArray';
    use Carp;

    sub EXTEND {
        my ($self, $size) = @_;
        croak "Cannot be empty" if 0 == @$self && 0 == $size;
        $self->SUPER::EXTEND($size)
    }

}

use parent -norequire => 'Array::Nonempty::Attr';

my %hash_ok = ( answer => 42 );
my %hash_empty = ();

my @keys_ok :Nonempty = keys %hash_ok;

my @keys_empty :Nonempty = keys %hash_empty;