Perl object is just a blessed hash

To work on a small testing utility, I have to pick up perl again. Fortunately my memory still served me well until I got into this problem. How to trun a hash into object. After a little reading of my Learning Perl book. I figured out how it works. Once you understand perl object is just a blessed hash, then the solution is clear.

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package MyTest;

use strict;

my %hash = (color=>"red", shape=>"round");
my $hashref = \%hash;

sub not_typical_new {
 my ($proto, $arg) = @_;
 my $class = ref($proto) || $proto;
 my $self = $arg;
 bless ($self, $class);
 return $self;
}

my $obj = mytest->not_typical_new($hashref);
print $obj->{color}, "\n";