Reading in a dumped hash reference works in the perl debugger but not in the code.

[Anonymous Monk]

Hi all.

I'm trying to read in a hash reference dumped to a file with Data::Dumper via an eval with no success. After much frustration I've discovered this works fine in the debugger, but not in the code. I was hoping someone could explain why.

I know there are better ways to do this (Storable, etc.) but I need a plain text version of the data and, more importantly, I'd like to know why this happens differently in the debugger.

  
#perl v5.10.1

my $testdata;
open(DATA, "<filename") or die $!;
{
    local $/;
    $DB::single=1;
    $testdata = eval <DATA>;
}
close DATA;

#testdata will be undefined

However, when using the debugger:

DB<2> $testdata = eval <DATA>;
DB<3> x $testdata
#outputs the expected data

Thanks for your time.

[LanX]

DATA is a predefined keyword, plz use something different. (but not END ;-)

see Special Literals in perldata

[Anonymous Monk]

Thanks for the tip LanX, I'll keep that in mind. :)

Using NOTDATA for the file handle yields the same results

[Ken Slater]

Not sure if I have enough info, but the following seems to work for me on Windows XP, ActiveState Perl 5.8.9.

use strict;
use warnings;
use Data::Dumper;

my $filename = 'hashref.txt';

my $hashRef = {a => '1',
               b => '2'};

open my $FH, '>', $filename or die
   "Unable to open $filename for output: $^E\n";

print $FH Dumper $hashRef;

close $FH;

my $testdata;

#  Since I'm using 'strict', must declare $VAR1 as it is used in
#  the dump file.
my $VAR1;

open $FH, '<', $filename or die $!;
{
    local $/;
    # Not sure what this line is for
    #  $DB::single=1;
    $testdata = eval <$FH>;
}
close $FH;

while (my ($key,$value) = each(%$testdata))
{
   print "$key $value\n";
}
#
#  This is what the file hashref.txt looks loke
#
__DATA__
$VAR1 = {
          'a' => '1',
          'b' => '2'
        };

HTH, Ken

[Anonymous Monk]

Thanks Ken. Unfortunately $testdata is still undefined when I use your code to read in my file. What's strange is that the dumped file seems perfectly valid. If I take a copy of the dumped data from the file and paste it into the code and compare it against the hash generated before it's dumped it works just fine.