I am writing a module (App::DB::Backup, which uses Moose) which `extends 'App::Base', 'App::DB';` App::DB also `extends 'App::Base';` (which both also use Moose). One of the new module's attributes has a default which wants to use a ->cfg attribute provided by the ::Base class. But trying to instantiate my new class gives me a 'Attribute (cfg) d…

gistfile1.txt

-----------------------------
the errors I am seeing
-----------------------------

$ perl t/9999-app-db-backup.t 
# Testing App::DB::Backup
ok 1 - use App::DB::Backup;
Attribute (cfg) does not pass the type constraint because: Validation failed for 'Config::Simple' with value undef (not isa Config::Simple) at /usr/local/lib/perl/5.10.1/Moose/Meta/Attribute.pm line 1274
        Moose::Meta::Attribute::verify_against_type_constraint('Moose::Meta::Attribute=HASH(0x9c3dd98)', undef, 'instance', 'App::DB::Backup=HASH(0x9ce6f10)') called at /usr/local/lib/perl/5.10.1/Moose/Meta/Attribute.pm line 1261
        Moose::Meta::Attribute::_coerce_and_verify('Moose::Meta::Attribute=HASH(0x9c3dd98)', undef, 'App::DB::Backup=HASH(0x9ce6f10)') called at /usr/local/lib/perl/5.10.1/Moose/Meta/Attribute.pm line 531
        Moose::Meta::Attribute::initialize_instance_slot('Moose::Meta::Attribute=HASH(0x9c3dd98)', 'Moose::Meta::Instance=HASH(0x9cf8058)', 'App::DB::Backup=HASH(0x9ce6f10)', 'HASH(0x97ca698)') called at /usr/local/lib/perl/5.10.1/Class/MOP/Class.pm line 525
        Class::MOP::Class::_construct_instance('Moose::Meta::Class=HASH(0x9a110f8)', 'HASH(0x97ca698)') called at /usr/local/lib/perl/5.10.1/Class/MOP/Class.pm line 498
        Class::MOP::Class::new_object('Moose::Meta::Class=HASH(0x9a110f8)', 'HASH(0x97ca698)') called at /usr/local/lib/perl/5.10.1/Moose/Meta/Class.pm line 274
        Moose::Meta::Class::new_object('Moose::Meta::Class=HASH(0x9a110f8)', 'HASH(0x97ca698)') called at /usr/local/lib/perl/5.10.1/Moose/Object.pm line 28
        Moose::Object::new('App::DB::Backup', 'HASH(0x942e2d0)') called at t/9999-app-db-backup.t line 13
# Tests were run but no plan was declared and done_testing() was not seen.

-----------------------------
t/9999-app-db-backup.t
-----------------------------

#!/usr/bin/perl
use strict;
use warnings;
use Test::More;

use lib qw( /home/hesco/sandbox/App/lib );
use App::DB::Backup;

diag( "Testing App::DB::Backup" );
use_ok( 'App::DB::Backup' );

my $ini = '/etc/app/db_backups.ini';
my $bu = App::DB::Backup->new({
     config_files => [ $ini ], 
    });

isa_ok( $bu, 'App::DB::Backup' );
isa_ok( $bu->file_util, 'File::Util' );
isa_ok( $bu->dbh, 'DBI::db' );

done_testing();
exit;

-----------------------------
lib/App/DB.pm
-----------------------------

package App::DB;

use Moose;
use DBI;
use Data::Dumper;

use lib qw( lib );
# use App::Base;
extends 'App::Base';

#  Connect to a database server

sub connect {
  my $self = shift;
  my $db = shift;

  # print STDERR "->connect() says that \$db is: " . Dumper(\$db);

  my $db_driver = $db->{'db_driver'};
  my $host_name = $db->{'db_host'};
  my $db_name = $db->{'db_name'};
  my $USER = $db->{'db_user'};
  my $PASSWORD = $db->{'db_pw'};

  my $dsn = "DBI:$db_driver:host=$host_name;database=$db_name";
  if($db->{'db_ssl'}){
    $dsn .= ';sslmode=require';
  }

  print "dsn: $dsn, user: $USER, pw: $PASSWORD \n"
      if($db->{'db_debug'});

  my @caller = caller();
  return (DBI->connect($dsn,$USER,$PASSWORD,
      {PrintError => 0, RaiseError => 1}))
        or print STDERR Dumper( \@caller );
}

1; # End of App::DB

-----------------------------
lib/App/Base.pm
-----------------------------

package App::Base;

use Moose;
use Carp;
use Data::Dumper;
use File::Path qw( mkpath );
use Config::Simple::Extended;

use lib qw( lib );
use App::DB;

has 'debug' => (
    is => 'rw',
   isa => 'Int',
);

has 'cfg' => (
         is => 'rw',
        isa => 'Config::Simple',
    builder => '_build_cfg',
);

has 'config_files' => (
          is => 'rw',
         isa => 'ArrayRef[Str]',
);
#   required => 1,

has 'configuration' => (
            is => 'rw',
           isa => 'Config::Simple',
);

has 'dbh' => (
            is => 'rw',
           isa => 'DBI::db',
    lazy_build => 1,
);

sub _build_cfg {
    my $self = shift;
    # warn '->_build_cfg gets a $self object: ' . Dumper( $self );
    if(defined($self->configuration)){
        return $self->configuration;
    } elsif(defined($self->config_files)){
        print STDERR "We have a config_files key which includes: " .
            Dumper( $self->config_files )
                if( $self->debug );
        my $cfg;
        undef($cfg);
        foreach my $file (@{$self->config_files}){
            print "Now applying $file to configuration hash \n"
                if( $self->debug );
            $cfg = Config::Simple::Extended->inherit({
                      debug => $self->debug,
                base_config => $cfg,
                   filename => $file });
        }
        print Dumper( $cfg->get_block("paths") )
            if( $self->debug );
        return $cfg;
    } else {
      my @caller = caller();
      die "App::Base's constructor invoked with no Confirguration File.\n"
          . Dumper( $self, \@caller );
    }
}

sub _build_dbh {
    my $self = shift;
    my $db = $self->cfg->get_block('db');
    my $dbh = App::DB->connect($db);
    return $dbh;
}

1; # End of App::Base

-----------------------------