Re: DBI 1.15 subclassing bug!

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To: "dbi-users" <dbi-users@perl.org> 
Subject: Re: DBI 1.15 subclassing bug! 
From: "Phil R Lawrence" <prlawrence@Lehigh.EDU> 
Date: Mon, 9 Apr 2001 11:40:39 -0400 
Cc: "Tim Bunce" <Tim.Bunce@ig.co.uk> 
Delivered-To: mailing list dbi-users@perl.org 
Mailing-List: contact dbi-users-help@perl.org; run by ezmlm 
References: <00a501c0bede$2b70be00$5b34b480@lehigh.edu> <20010407000509.F20472@ig.co.uk> 

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"Tim Bunce" <Tim.Bunce@ig.co.uk> wrote:
> On Fri, Apr 06, 2001 at 05:11:38PM -0400, Phil R Lawrence wrote:
> >   Uncaught exception from user code:
> >         DBI->disconnect is not a DBI method...
> I wouldn't want to call you a beginner, but somewhere, for some
> reason, you're executing "DBI->disconnect" or "$foo->disconnect"
> where $foo contains "DBI".

You were kind to not call me a beginner!  Nonetheless, the issue was a
screwed up @ISA ordering.  See below for the bug.

I'm glad you added the code to make DBI->disconnect blow up in DBI
1.15.  I learned a bit more about inheritance as a result.

Thanks,
Phil R Lawrence


package STORIT;
use SUBCLASS_DBI;
use vars qw( @ISA );
@ISA = qw ( SUBCLASS_DBI );

sub new {
    my $proto = shift;
    my $class = ref($proto) || $proto;
    my $s = $class->test_connect or die;

    return $s;
}

#==============================================================
package STORIT::db;
use vars qw( @ISA );
@ISA = qw( STORIT SUBCLASS_DBI::db );
    #      ^^^^^^
    #      this caused disconnect invocation to be first looked
    #      for as a DBI method (due to STORIT's @ISA) instead
    #      of as a SUBCLASS_DBI::db method (which would have
    #      correctly resolved as a DBI::db method).

#==============================================================
package STORIT::st;
use vars qw( @ISA );
@ISA = qw(SUBCLASS_DBI::st);