use strict;
use warnings;

use configthing qw();

our configthing $cfg = new configthing;

use Data::Dumper;
print Dumper $cfg;

##</code><code>##

package configthing;

use strict;
use warnings;

use fields qw(
  a
  b
  c
  d
);

our %DEFAULTS = (
	b => 'default for b',
	c => 'default for c'
);

1;

sub new {
	my $this = shift;

	unless (ref $this) {
		$this = fields::new($this);
	}

	our %FIELDS;
	foreach my $k ( keys(%FIELDS) ) {
		$this->{$k} = '' unless defined($this->{$k});
	}

	$this->{a} = 'set at initialization';

	foreach my $k ( keys(%DEFAULTS) ) {
		$this->{$k} = $DEFAULTS{$k};
	}

	return $this;
}

##</code><code>##

$VAR1 = bless( [
                 bless( {
                          'c' => 3,
                          'a' => 1,
                          'b' => 2,
                          'd' => 4
                        }, 'pseudohash' ),
                 'set at initialization',
                 'default for b',
                 'default for c',
                 ''
               ], 'configthing' );

##</code><code>##

$VAR1 = bless( {
                 'c' => 'default for c',
                 'a' => 'set at initialization',
                 'b' => 'default for b',
                 'd' => ''
               }, 'configthing' );