> On Wed, Oct 13, 2004 at 04:33:14PM -0400, Marc M. Adkins wrote:
> > I have been getting an annoying warning about dereferencing
> an unreferenced
> > scalar. Sometimes it comes out in such a way that it
> misses $SIG{__WARN__}
> > redirection. After much trial and error I tracked it down, sort of.
> >
> > Here's the punch line: it doesn't happen unless I use
> fetchall_hashref().
>
> It's fixed in the (as yet unannounced) DBI 1.45 release.
Yesterday (10/22) I found that ActiveState had updated their PPM repository
and I downloaded and installed DBI 1.45:
ppm> query DBI
Querying target 1 (ActivePerl 5.8.4.810)
1. DBI [1.45] Database independent interface for Perl
ppm> query DBD-ODBC
Querying target 1 (ActivePerl 5.8.4.810)
1. DBD-ODBC [1.11] ODBC Driver for DBI
ppm>
Unfortunately, my test program (attached, same as previous version) is still
saying the same thing (two runs, second demonstrates problem):
D:\CaseLaw>c:\temp\unref.pl
Step 1: Database query
16392: db_denydatareader
16393: db_denydatawriter
3: INFORMATION_SCHEMA
16384: db_owner
2: guest
16390: db_datareader
16385: db_accessadmin
16389: db_backupoperator
1: dbo
4: system_function_schema
16391: db_datawriter
0: public
16386: db_securityadmin
16387: db_ddladmin
5: servman
Step 2: Copy files
Copied readme.txt
Copied shortcut.cpp
Copied SHORTCUT.DEF
Copied Shortcut.MAK
Copied Shortcut300.MAK
D:\CaseLaw>c:\temp\unref.pl 1
Step 1: Database query
16392: db_denydatareader
16393: db_denydatawriter
3: INFORMATION_SCHEMA
16384: db_owner
2: guest
16390: db_datareader
16385: db_accessadmin
16389: db_backupoperator
1: dbo
4: system_function_schema
16391: db_datawriter
0: public
16386: db_securityadmin
16387: db_ddladmin
5: servman
Step 2: Copy files
Attempt to free unreferenced scalar: SV 0x1c6ca04 at
C:/Perl/lib/File/Copy.pm line 91.
Copied readme.txt
Attempt to free unreferenced scalar: SV 0x1c66d9c at
C:/Perl/lib/File/Copy.pm line 91.
Copied shortcut.cpp
Attempt to free unreferenced scalar: SV 0x1c66dfc at
C:/Perl/lib/File/Copy.pm line 91.
Copied SHORTCUT.DEF
Attempt to free unreferenced scalar: SV 0x1c6e89c at
C:/Perl/lib/File/Copy.pm line 91.
Copied Shortcut.MAK
Attempt to free unreferenced scalar: SV 0x1c6e8a8 at
C:/Perl/lib/File/Copy.pm line 91.
Copied Shortcut300.MAK
D:\CaseLaw>
This is Windows 2000, ActiveState Perl 5.8.4. I didn't think to check the
version of File::Copy. But the problem is connected somehow to (non-)use of
fetchall_hashref().
Is there anything I can do to test this further that doesn't require a C
compiler / debugger? We aren't provided with those tools (or the time to use
them) at work and I don't have a working Windows system at home any more.
This is not a showstopper for me. I've already modified all of my code to
avoid fetchall_hashref(). Well, almost all of my code, I still see the error
from time to time so I must have missed something somewhere...
mma
use strict;
use warnings;
use DBI;
use File::Copy;
use File::Path;
use File::Spec;
use constant TEMP_DIR => 'C:\\\temp';
print "Step 1: Database query\n";
my $DSN = 'DBI:ODBC:' . join ';', split /\n/s, <<DSN;
DRIVER=SQL Server
Trusted_Connection=Yes
APP=Microsoft Open Database Connectivity
DATABASE=master
SERVER=Tech14
DSN
my $dbms = DBI->connect($DSN, undef, undef, {
AutoCommit => 1,
PrintError => 0,
RaiseError => 1
});
my $stmt = $dbms->prepare(<<SQL);
select *
from sysusers
SQL
$stmt->execute;
my $list = undef;
if (@ARGV) {
# This causes:
# Attempt to free unreferenced scalar
# errors:
$list = $stmt->fetchall_hashref('uid');
} else {
# This doesn't cause the error:
my %list = ( );
while (my $rec = $stmt->fetchrow_hashref) {
$list{$rec->{uid}} = $rec;
}
$list = \%list;
}
$stmt->finish;
printf " %8d: %s\n", $_->{uid}, $_->{name}
for values %$list;
print "Step 2: Copy files\n";
my $dstDir = File::Spec->catfile(TEMP_DIR, 'dest');
my $srcDir = File::Spec->catfile(TEMP_DIR, 'source');
rmtree($dstDir);
mkpath($dstDir);
die "Unable to open source directory\n $!\n"
unless opendir SOURCE, $srcDir;
while (my $item = readdir(SOURCE)) {
next if $item =~ /^\./;
my $dst = File::Spec->catfile($dstDir, $item);
my $src = File::Spec->catfile($srcDir, $item);
# The unreferenced scalar error occurs here...
if (copy($src, $dst)) {
print " Copied $item\n";
} else {
warn " Unable to copy $item\n $!\n"
}
}
closedir SOURCE;
