Wally Hartshorn has asked for the wisdom of the Perl Monks concerning the following question:

Okay, this is bizarre. In one particular program (which uses Class::DBI), when I "use diagnostics", the program fails to compile, complaining that it cannot find "DBI/db.pm". If I "use warnings" instead, the program compiles fine and runs perfectly.

Consider the following code (stripped of all useful statements), which you can use on your system to determine whether you get the same behavior:

mydemo.pl

#!/usr/bin/perl

use strict;
use diagnostics; # use warnings works

use lib ".";
use MyTable;

[download]

MyTable.pm

package MyTable;
use base 'MyDatabase';

1;

[download]

MyDatabase.pm

package MyDatabase;
use base 'Class::DBI';

1;

[download]

When I try to run "mydemo.pl" with "use diagnostics", I get a boatload of errors about being unable to load "DBI/db.pm". Here's a few lines from the start:

Uncaught exception from user code:
        Uncaught exception from user code:
        Uncaught exception from user code:
        Uncaught exception from user code:
        Uncaught exception from user code:
        Uncaught exception from user code:
        Uncaught exception from user code:
        Uncaught exception from user code:
        Uncaught exception from user code:
        Uncaught exception from user code:
        Uncaught exception from user code:
        Uncaught exception from user code:
        Uncaught exception from user code:
        Uncaught exception from user code:
        Can't locate DBI/db.pm in @INC (@INC contains: . /usr/local/li
+b/perl5/5.6.1/sun4-
solaris /usr/local/lib/perl5/5.6.1 /usr/local/lib/perl5/site
_perl/5.6.1/sun4-
solaris /usr/local/lib/perl5/site_perl/5.6.1 /usr/local/lib/
perl5/site_perl/5.6.0/sun4-
solaris /usr/local/lib/perl5/site_perl/5.6.0 /usr/local/lib/
perl5/site_perl/5.005/sun4-
solaris /usr/local/lib/perl5/site_perl/5.005 /usr/local/lib/
perl5/site_perl) at (eval 6) line 3.
        eval 'require DBI::db
;' called at /usr/local/lib/perl5/5.6.1/base.pm line 59
        base::import('base', 'DBI::db') called 
at /usr/local/lib/perl5/site_perl/5.6.1/Ima/DBI.pm line 645
        Ima::DBI::db::BEGIN() called at DBI/db.pm line 0
        eval {...} called at DBI/db.pm line 0
        require Ima/DBI.pm called at (eval 5) line 3
        eval 'require Ima::DBI
;' called at /usr/local/lib/perl5/5.6.1/base.pm line 59
        base::import('base', 'Class::Accessor', 'Class::Data::Inherita
+ble', 'Ima
::DBI') called 
at /usr/local/lib/perl5/site_perl/5.6.1/Class/DBI.pm line 6
        Class::DBI::__::Base::BEGIN() called at DBI/db.pm 
line 0
        eval {...} called at DBI/db.pm line 0
        require Class/DBI.pm called at (eval 3) line 3
        eval 'require Class::DBI
;' called at /usr/local/lib/perl5/5.6.1/base.pm line 59

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It goes on and on like that. Just change "diagnostics" to "warnings" and the problems go away (not to mention that, with the actual code in place, the program works).

What kind of weirdness have I stumbled across? Has anyone else seen something like this? (I spent about 5 hours trying to figure out why one program was working while a similar program -- use had the "use diagnostics" line -- was not!) This is Perl 5.6.1 under Sun Solaris 7.

Wally Hartshorn

(Plug: Visit JavaJunkies, PerlMonks for Java)

Replies are listed 'Best First'.
Re: Why Does My Class::DBI Program Break Under "use diagnostics" Pragma?
by pfaut (Priest) on Jul 12, 2003 at 12:12 UTC

    I just entered the code on your base node and it works fine on my system. Perl 5.6.1 on linux with Class::DBI 0.91.

    90% of every Perl application is already written. ⇒
    dragonchild
[reply]
(jeffa) Re: Why Does My Class::DBI Program Break Under "use diagnostics" Pragma?
by jeffa (Bishop) on Jul 12, 2003 at 15:48 UTC
    Unlike pfaut, i tried your code and it failed in the same manner. I used Class::DBI version 0.93 on two Linux boxes - one with Perl 5.6.0 and the other with 5.6.1. Both failed. One bizarre item that i can't figure out about this is that there is no DBI/dbi.pm file ... DBI::db is sort of automagically created somewhere inside of DBI.pm (note there there is no DBI::db package declaration either). I wonder how pfaut was able to get your code to work ...

    jeffa

    L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
B--B--B--B--B--B--B--B--
H---H---H---H---H---H---
(the triplet paradiddle with high-hat)
[reply]

      I looked at %INC after the program got started and dumped versions. Here's what I got. The code:

      #!/usr/bin/perl
use strict;
use diagnostics;
use lib ".";
use MyTable;

print <<"END";
Exporter = $Exporter::VERSION
Carp = $Carp::VERSION
XSLoader = $XSLoader::VERSION
Class::DBI::Query = $Class::DBI::Query::VERSION
DynaLoader = $DynaLoader::VERSION
lib = $lib::VERSION
Class::Trigger = $Class::Trigger::VERSION
Exporter::Heavy = $Exporter::Heavy::VERSION
DBI = $DBI::VERSION
Class::WhiteHole = $Class::WhiteHole::VERSION
MyDatabase = $MyDatabase::VERSION
constant = $constant::VERSION
Class::DBI::ColumnGrouper = $Class::DBI::ColumnGrouper::VERSION
strict = $strict::VERSION
diagnostics = $diagnostics::VERSION
base = $base::VERSION
vars = $vars::VERSION
Config = $Config::VERSION
warnings::register = $warnings::register::VERSION
warnings = $warnings::VERSION
Class::Data::Inheritable = $Class::Data::Inheritable::VERSION
Ima::DBI = $Ima::DBI::VERSION
Class::Accessor = $Class::Accessor::VERSION
MyTable = $MyTable::VERSION
Class::DBI = $Class::DBI::VERSION
overload = $overload::VERSION
AutoLoader = $AutoLoader::VERSION
Data::Dumper = $Data::Dumper::VERSION
END

      [download]

      The output:

      Exporter = 5.562
Carp =
XSLoader = 0.01
Class::DBI::Query =
DynaLoader = 1.04
lib = 0.5564
Class::Trigger = 0.08
Exporter::Heavy =
DBI = 1.32
Class::WhiteHole = 0.03
MyDatabase = -1, set by base.pm
constant = 1.02
Class::DBI::ColumnGrouper =
strict = 1.01
diagnostics =
base = 1.98
vars =
Config =
warnings::register =
warnings =
Class::Data::Inheritable = 0.02
Ima::DBI = 0.28
Class::Accessor = 0.17
MyTable =
Class::DBI = 0.91
overload =
AutoLoader = 5.58
Data::Dumper = 2.102

      [download]
      90% of every Perl application is already written. ⇒
      dragonchild
[reply]
[d/l]
[select]

      Well, I'm still not sure what the cause was, but I figured out how to fix it -- upgrade to Perl 5.8.0. :-) I had been using Perl 5.6.1 and Class::DBI 0.92. Switching to Perl 5.8.0 made the problem go away. I don't know if I just had some weirdness in my configuration or if it was an odd conflict between 5.6.1 and 0.92. In any case, it works now and I'm tired of struggling with it.

      Weird. And one of the biggest time-sucks I've ever had the misfortune to get pulled into. :-(

      Thanks for verifying that I wasn't 100% nuts!

      Wally Hartshorn

      (Plug: Visit JavaJunkies, PerlMonks for Java)

[reply]

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