Re: How to modify a warning message within a sub?

I read about installing a __WARN__ signal handler, but that appears to require exposing $arrayRef to a wider scope.

No. Did you try? The trick is to install a local $SIG{__WARN__}:

sub compareLT105
{
   my $arrayRef = shift;

   { # bare block to narrow scope of local()

      local $SIG{__WARN__} = sub {
         chomp( my $msg = $_[0] );
         print STDERR $msg," \$arrayRef = [qw(@{$arrayRef})]\n";
      };
      return 'true' if $arrayRef->[1] < 105;

   }

   return 'false';
}
For 100 compareLT105 says: true
For 106 compareLT105 says: false
Argument "100A" isn't numeric in numeric lt (<) at warn.pl line 27. $a
+rrayRef = [qw(3 100A)]
For 100A compareLT105 says: true
Argument "100B2" isn't numeric in numeric lt (<) at warn.pl line 27. $
+arrayRef = [qw(4 100B2)]
For 100B2 compareLT105 says: true
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Re^2: How to modify a warning message within a sub? by Marshall (Canon) on Aug 09, 2011 at 03:53 UTC
THANKS!, I worked some more...this works.. The good thing is that `$arrayRef->[1]` works without having $arrayRef having more scope than within the sub{}. #!/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; local $SIG{__WARN__} = sub { my $msg = shift; print STDERR $msg,"******"; print STDERR "error array index: ",$arrayRef->[0]; print STDERR " value is ",$arrayRef->[1], "\n"; }; 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 30. ****error array index: 3 value is 100A For 100A compareLT105 says: true Argument "100B2" isn't numeric in numeric lt (<) at C:\TEMP\warnexampl +e.pl line 30. ******error array index: 4 value is 100B2 For 100B2 compareLT105 says: true [download]	[reply] [d/l] [select]

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Re^2: How to modify a warning message within a sub?
by Marshall (Canon) on Aug 09, 2011 at 03:53 UTC

$arrayRef->[1]

#!/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;
   
   local $SIG{__WARN__} = 
      sub 
      {
          my $msg = shift;
          print STDERR $msg,"********";
          print STDERR "error array index: ",$arrayRef->[0]; 
          print STDERR " value is ",$arrayRef->[1], "\n";  
      };
  
   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 30.
********error array index: 3 value is 100A
For 100A compareLT105 says: true
Argument "100B2" isn't numeric in numeric lt (<) at C:\TEMP\warnexampl
+e.pl line 30.
********error array index: 4 value is 100B2
For 100B2 compareLT105 says: true
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