package MyObj;

sub new {
   bless {}, shift;
}

1;

---

#!/usr/bin/perl -w

use MyObj;

my %hash;

my $a = MyObj->new();
my $b = MyObj->new();

$hash{$a} = "This is my Object A";
$hash{$b} = "This is my Object B";

print $a, "\n";
print $b, "\n";

print $_, " : ", $hash{$_}, "\n" foreach keys %hash;

__END__
MyObj=HASH(0x2001b1fc)
MyObj=HASH(0x2001b2e0)
MyObj=HASH(0x2001b1fc) : This is my Object A
MyObj=HASH(0x2001b2e0) : This is my Object B