I thought I pretty much understood inheritance, but I am missing something in my latest attempt. I am trying to make a simple class that inherits from DBIx::SQLEngine. I have not attempted to add any methods, just to implement a new() method in MY class that generates an object that @ISA DBIx::SQLEngine. I keep getting an error that looks like I am not actually inheriting any methods from DBIx::SQLEngine. Here is the simple module code (and made change to call to SUPER::new() directly--thanks frodo72):

package Bio::DB::UCSC::DB;
use strict;

use DBIx::SQLEngine;
our @ISA = qw/DBIx::SQLEngine/;

sub new {
    my $proto = shift;
    my $class = $proto;
    my $self  = $class->SUPER::new(@_);

    bless($self, $class);

    return($self);
}

1;

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And here is a little test script, debugger output, and error message: 
#!/usr/bin/perl
use strict;

use Bio::DB::UCSC::DB;
use DBIx::SQLEngine;

my $db = Bio::DB::UCSC::DB->new('dbi:mysql:database=hg18','uname','pas
+swd');

my $sqldb = DBIx::SQLEngine->new('dbi:mysql:database=hg18','uname','pa
+sswd');

my $refGenes1 = $sqldb->fetch_select(
  tables => {'refGene.name' => 'refLink.mrnaAcc'},
  where => ['refGene.name like ?','NM_0002%']);

my $refGenes = $db->fetch_select(
  tables => {'refGene.name' => 'refLink.mrnaAcc'},
  where => ['refGene.name like ?','NM_0002%']);

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From the debugger, I dump out the $db and $sqldb objects, which look like: 
  DB<3> x $sqldb
0  DBIx::SQLEngine::Driver::Mysql::V3_0=HASH(0x1a7c478)
   'dbh' => DBI::db=HASH(0x1a28f78)
        empty hash
   'package' => 'DBIx::SQLEngine::Driver'
   'reconnector' => CODE(0x1a7c4a8)
      -> &DBIx::SQLEngine::Driver::__ANON__[/Library/Perl/5.8.1/DBIx/S
+QLEngine/Driver.pm:252] in /Library/Perl/5.8.1/DBIx/SQLEngine/Driver.
+pm:252-252
  DB<4> x $db
0  Bio::DB::UCSC::DB=HASH(0x1a28f54)
   'dbh' => DBI::db=HASH(0x15c1fb8)
        empty hash
   'package' => 'DBIx::SQLEngine::Driver'
   'reconnector' => CODE(0x1a29938)
      -> &DBIx::SQLEngine::Driver::__ANON__[/Library/Perl/5.8.1/DBIx/S
+QLEngine/Driver.pm:252] in /Library/Perl/5.8.1/DBIx/SQLEngine/Driver.
+pm:252-252

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So, they look OK, but I get an error when I try to use the $db object: 
main::(test.pl:16):     my $refGenes = $db->fetch_select(tables => {'r
+efGene.name' => 'refLink.mrnaAcc'},
main::(test.pl:17):                                      where => ['re
+fGene.name like ?','NM_0002%']);
  DB<1> 
Can't locate object method "fetch_select" via package "Bio::DB::UCSC::
+DB" at test.pl line 16.
 at test.pl line 16
Debugged program terminated.  Use q to quit or R to restart,

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Any hints are appreciated.

Thanks,
Sean

In reply to Inheritance confusion by srdst13

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