sub _share {
            
    my $it = shift;
    my $ref = ref $it;

    if ($ref eq 'SCALAR') {
        tie ${$it},'threads::shared',{},${$it};
    } elsif ($ref eq 'ARRAY') {
        tie @{$it},'threads::shared',{},@{$it};
    } elsif ($ref eq 'HASH') {
        tie %{$it},'threads::shared',{},%{$it};
    } elsif ($ref eq 'GLOB') {
        tie *{$it},'threads::shared',{},*{$it};
    } else {
        _croak( "Don't know how to share '$it'" );
    }
} #_share

##</code><code>##

BEGIN {
    no strict 'refs';

# same handler for all types, so we loop through them

    foreach my $type (qw(SCALAR ARRAY HASH)) {
        my $name = "UNIVERSAL::MODIFY_${type}_ATTRIBUTES";
        my $old = \&$name;

# Install our new attribute handler

        *$name = sub {
            my ($package,$ref,@attribute) = @_;
            _share( $ref ) if grep m#^shared$#, @attribute;

# handle other attributes, is this needed?

            if (@attribute = grep !m#^shared$#,@attribute) {
                @attribute = $old->( $package,$ref,@attribute );
            }
            return @attribute;
        } #$name
    }
} #BEGIN