Perl Module Error - defined(%hash) is deprecated - linux

Question

Background:
I am working to migrate a Linux server to a newer one from Ubuntu 10.04 to 12.04
This server is responsible for executing several a number of Perl modules via crontabs.
These Perl Modules rely heavily on 30-40 perl extensions.
I have installed all Perl extensions and the crontabs are able to process successfully except for several Syntax errors caused by the newer versions of these Perl extensions.
I need some help with modifying the syntax to get the Perl script to process as intended.
Errors:
defined(%hash) is deprecated at pm/Alerts/Alerts.pm line 943.
(Maybe you should just omit the defined()?)
defined(%hash) is deprecated at pm/Alerts/Alerts.pm line 944.
(Maybe you should just omit the defined()?)
Code:
###
# Iterate the arrays deleting identical counts from each.
# If we found a mismatch then die.
# If either array is not empty when we are done then die
$logger->info('Comparing ' . (scalar keys %cms_rows) . ' CMS symbols to ' . (scalar keys %stats_rows) . ' STATS symbols');
foreach my $symbol ( keys %cms_rows ) {
my %cms_row = delete $cms_rows{$symbol};
my %stats_row = delete $stats_rows{$symbol};
##LINE 943## die("Error: NULL CMS counts for symbol '$symbol'") unless defined %cms_row;
##LINE 944## die("Error: NULL Stats counts for symbol '$symbol'") unless defined %stats_row;
my $cms_json = encode_json(\%cms_row);
my $stats_json = encode_json(\%stats_row);
$logger->debug("Comparing counts for '$symbol': CMS($cms_json), Stats($stats_json)");
die("Error: Up Counts Don't match for symbol '$symbol': CMS($cms_json), Stats($stats_json)") unless (!defined $cms_row{1} && !defined $stats_row{1}) || $cms_row{1} == $stats_row{1};
die("Error: Down Counts Don't match for symbol '$symbol': CMS($cms_json), Stats($stats_json)") unless (!defined $cms_row{-1} && !defined $stats_row{-1}) || $cms_row{-1} == $stats_row{-1};
}
###
Hopefully someone can help with this, any help is appreciated.

Answer 1

You must have upgraded from a seriously old version of Perl. The Perl 5.6.1 release notes say:
defined(%hash) is deprecated
(D) defined() is not usually useful on hashes because it checks for an
undefined scalar value. If you want to see if the hash is empty, just
use if (%hash) { # not empty } for example.
It was always a pretty stupid thing to do and Perl now warns you that you're doing something stupid. The warning is pretty clear about what you should do to fix this:
Maybe you should just omit the defined()?
So your lines would become:
die("Error: NULL CMS counts for symbol '$symbol'") unless %cms_row;
die("Error: NULL Stats counts for symbol '$symbol'") unless %stats_row;