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

my %hash = (
	key1 => 'value',
	key2 => undef,
	key3 => {},
	key4 => { foo => 99 },
);

foreach my $key (qw(key1 key2 key3 key4)) {
	my $reftype = ref ($hash{$key});
	if ($reftype && $reftype eq 'HASH') {
		my $entries = scalar keys %{$hash{$key}};
		print "\$hash{$key} is a hashref which is " .
			($entries ? 'not ' : '') . "empty.\n";
	} else {
		print "\$hash{$key} is not a hashref\n";
	}
}