Binary data structure to moose class.

[chrestomanci]

Greeting wise brothers.

I am looking a Moose class reprentation of a binary file format. (The binary file is the metadata file format used by Humax Digital satelite TV recevers. Documented here: http://foxsatdisk.wikispaces.com/.hmt+file+format)

Seeing as the Moose BestPractices discorage overiding new(), the approach I am taking is to insert the raw data as a field in the class, and then have a large number of lazy builders to extract fields. My API currenlty looks like this:

my $hmt_data = new Binary::Humax::hmt_data();      # Object will be us
+eless as it contains no data
$hmt_data->raw_from_file($path_name);              # At this point onl
+y the 'rawData' field is populated
my $field = $hmt_data->startTime();                # Invokes a lazy bu
+ilder to extract the field.

Some of the code in the class looks like this

use DateTime;
use Moose;

# The raw data that all the fields are extracted from.
has 'rawDataBlock' => (
      is  => 'rw',
      isa => 'Str',
);

# All the fields extracted from the raw data block are lazy using buil
+ders below.
has 'lastPlay'        => ( lazy_build => 1, is=>'rw', isa=>'Int');
has 'ChanNum'         => ( lazy_build => 1, is=>'rw', isa=>'Int');
has 'startTime'       => ( lazy_build => 1, is=>'rw', isa=>'DateTime')
+;
has 'fileName'        => ( lazy_build => 1, is=>'rw', isa=>'Str');

[...]

sub _build_lastPlay
{
    my $self = shift @_;
    return unpack('@5 S', $self->rawDataBlock() );
}

sub _build_ChanNum
{
    my $self = shift @_;
    return unpack('@17 S', $self->rawDataBlock() );
}

sub _build_startTime
{
    my $self = shift @_;
    my $epoch = unpack('@25 N', $self->rawDataBlock() );
    return DateTime->from_epoch( epoch => $epoch, time_zone => 'GMT' )
+;
}

sub _build_fileName
{
    my $self = shift @_;
    return unpack('@33 A512', $self->rawDataBlock() );
}

My problem is that there are rather a lot of those lazy builders, and they are all similar and repetitive. Is there a way I can make all the fields share the same lazy builder, perhaps by putting the unpack information as an attribute to the field definition?

Secondly, when complete, I plan to upload the module to CPAN. Have I chosen a good name for it, or should it live in a different name space?