Let's say you know you will be making a hash of 120,000 hashes, each with (up to) 2 values. Instead of making 120,000 tiny hashes, with the overhead of each hash, you can go ahead and make 120,000 blessed scalar-refs and one huge array of 360,000 scalars. Each object will be a blessed scalar. Something like (untested!): 
package CoolObject;

my @objects;
my $next_index = 0;

sub new
{
    my $class = shift;

    my $x = $next_index;
    my $self = bless \$x, $class;
    $next_index += 3;

    return $self;
}

sub name
{
    my $self = shift;
    $object[$$self] = shift if @_;
    return $object[$$self];
}

sub attr1
{
    my $self = shift;
    $object[$$self + 1] = shift if @_;
    return $object[$$self + 1];
}

sub attr2
{
    my $self = shift;
    $object[$$self + 2] = shift if @_;
    return $object[$$self + 2];
}

1;

[download]
Those having read the Panther book will recognize this. Some obvious improvements would include:
  1. Adding the kind of garbage collection he had to re-use entries. (This would be in DESTROY.)
  2. Initialization of attributes. (This would be in new)
  3. Making it into more of a base class that will take attributes. (This would involve adding some sort of attribute registration.)
  4. Adding attribute inheritance. (This would involve attribute registration that walks the ISA-tree.)

------
We are the carpenters and bricklayers of the Information Age.

Don't go borrowing trouble. For programmers, this means Worry only about what you need to implement.

In reply to An interesting OO representation (was Re3: A memory efficient hash, trading off speed - does it already exist?) by dragonchild
in thread A memory efficient hash, trading off speed - does it already exist? by JPaul

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