Honored Monks.
I'm using Randal Schwartz's text Perl Objects, References & Modules to learn OOP with Perl. I've made it up to chapter 9, where I've encountered a problem with the exercise that I can't figure out.
Here's the code:
#!/usr/bin/perl -w
use strict;
{ package Animal;
    sub named {            # Constructor of instance - Objects
    my $class = shift;        # first argument is class name
    die "already an object. $!"
        if ref($class);        # only instances are references
    my $name = shift;        # 2nd arg is the object's identity
    my $self = {Name => $name, Color => $class->default_color}; 
    bless \$self, $class;        # create the object 
    }                    
    sub set_name {
    my $object = shift;        # first argument s/b an instance
      my $name = shift;        # 2nd parm s/b the new animal name
    if (ref $object) {
        $object->{Name} = $name;
    }
    else {die "It's a class variable, $!";}
    }
    sub name {
    my $self = shift;
    ref $self ? $self->{Name}
    : "Just another $self";        # Not an instance, hence no name
    }
}
{ package Horse;
    our @ISA = qw(Animal);
    sub default_color {"brown";}
}
my $tv_horse = Horse->named("Mr. Ed");
print $tv_horse->name, " is ",$tv_horse->name,"\n";
$tv_horse->set_name("Mister Ed");

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I'm able to successfully create the $tv_horse object, but when I try to use the 'set_name' or 'name' methods I get a 'Not a HASH reference at ./test_objects.pl line 22.' I've used the debugger and it looks to me like the object is a reference to a hash: 
  DB<7> x $object
0  Horse=REF(0x13080)
   -> HASH(0x191d8d0)
         'Color' => 'brown'
         'Name' => 'Mr. Ed'

[download]
If I use class, not instance, methods this all works correctly of course. Any suggestions?

In reply to 'Not a HASH reference' error using Objects by irwin

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