10. Inside out classes (Chapter 15)

(One of the recommendations was not to make variables part of your interface. I did that just the other day. Ooops.)

Instead of:

    sub new {
	my ($class, ...) = @_;
	... 
	return bless {}, $class;
    }
    sub get_foo {
	my ($self) = shift;
	return $self->{foo};
    }

Do this:

    {
	my %foo_of;
	sub new {
	    my ($class, ...) = @_;
	    ...
	    return bless \do {my $anon_scalar}, $class;
	}
	sub get_foo {
	    my ($self) = shift;
	    return $foo_of{$self};
	}
    }

Magically, you have encapsulation, and all that.