my $o = bless {}, 'ARRAY';
print "$o isa array" if UNIVERSAL::isa($o, 'ARRAY');

__END__
ARRAY=HASH(0x759c) isa array

##</code><code>##

use Scalar::Util qw(reftype);

my $hash_object = bless {}, 'ARRAY';
my $array_ref = [1,2,3];
my $array_object = bless [], 'Foo';

foreach ($hash_object, $array_ref, $array_object) {
	print "reftype of ", $_, " is ", reftype($_), "\n";
};

__END__
reftype of ARRAY=HASH(0x759c) is HASH
reftype of ARRAY(0x7650) is ARRAY
reftype of Foo=ARRAY(0x74b8) is ARRAY