sub new {
    my $class = shift;
    local $value = shift;

    return bless { datum => $value, glob => *value }, $class
}

##</code><code>##

sub value {
    my $self = shift;
    
    # return $self{glob}           # will never work

    return $self->{glob}           # might work
}

##</code><code>##

my $d = datum->new(42);
*d =  $d->value();

##</code><code>##

my $datum = \ $obj->{datum};

# and then
$$datum = ...;


##</code><code>##

$datum->{foo}=...;
push @$datum,...;