Sometimes, one of my comparison subroutines causes a run-time warning. Perl has an amazing ability to do "something reasonable" in a situation like this and I am happy with what Perl does.

But the warning message doesn't tell me enough to go quickly to the input record that caused the problem. This is demonstrated below.

What I would like to do is: if a warning happens within compareLT105(), is to print something specific to this particular subroutine call, like: $arrayRef->[0] in addition to the Perl generated warning. That would narrow the field from ~1 million records to one record.

I don't want to "die", I just want to add something to the warning message. I read about installing a __WARN__ signal handler, but that appears to require exposing $arrayRef to a wider scope. Block eval{} works with "die".

This is of course a very simplistic version of the "real thing", but I hope provides enough info to get me on the right track.

I hope the solution is so easy that it is a "Duh!". 

#!/usr/bin/perl -w
use strict;
$|=1;              #turns off buffering for STDOUT

my @x = ( [1,'100'],
          [2,'106'],
          [3,'100A'],
          [4,'100B2'],
        );
        
foreach my $ref (@x)
{
   print "For $ref->[1] compareLT105 says: ", 
                        compareLT105($ref),"\n";
}
        
sub compareLT105
{
   my $arrayRef = shift;
   
   return 'true' if $arrayRef->[1] < 105;
   return 'false';
}

__END__
For 100 compareLT105 says: true
For 106 compareLT105 says: false
Argument "100A" isn't numeric in numeric lt (<) at C:\TEMP\warnexample
+.pl line 21.
For 100A compareLT105 says: true
Argument "100B2" isn't numeric in numeric lt (<) at C:\TEMP\warnexampl
+e.pl line 21.
For 100B2 compareLT105 says: true

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In reply to How to modify a warning message within a sub? by Marshall

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