In the code below I would like the Hash filled in the subroutine FillHashOne() to be accessible as a reference in $Hash. However all I get is an empty hash ref.

I think I am missing the section of my brain that is needed to understand references. I have read all the tutorials and have used references many times, but then I run into a situation like this that stymies me.

All help and suggestions are appreciated!

Update: Duh! I messed up my closure and had it inside the subroutine. It works when I fixed that.

#!/usr/bin/perl
use strict;
use warnings;

use constant false            => 0;
use constant true             => 1;

$| = true;

use Data::Dumper;

my $Hash = {};

sub FillHashOne
{
   my %HashOne;
{
   my ($Key, $Value) = @_;

   if(!defined($Key))
      {
      return(\%HashOne);
      }
   else
      {
      $HashOne{$Key} = $Value;
      }
}
}

$Data::Dumper::Indent      = 3;
$Data::Dumper::Purity      = true;
$Data::Dumper::Varname     = 'Hash';
$Data::Dumper::Quotekeys   = true;

$Hash->{'One'} = 1;
$Hash->{'Two'} = 2;
$Hash->{'Three'} = 3;
$Hash->{'String'} = 'Foo Bar';

print __LINE__ . ":Main:\$Hash:\n" . Dumper($Hash);
for (my $i = 0; $i < 10; $i++)
   {
   FillHashOne($i, "Value:\[$i\]");
   }
$Hash->{'HashOne'} = FillHashOne(undef());
print __LINE__ . ":Main:\$Hash:\n" . Dumper($Hash);
[download]

Updated Code:

#!/usr/bin/perl
use strict;
use warnings;

use constant false            => 0;
use constant true             => 1;

$| = true;

use Data::Dumper;

my $Hash = {};

{
   my %HashOne;
sub FillHashOne
{
   my ($Key, $Value) = @_;

   if(!defined($Key))
      {
      return(\%HashOne);
      }
   else
      {
      $HashOne{$Key} = $Value;
      }
}
}

$Data::Dumper::Indent      = 3;
$Data::Dumper::Purity      = true;
$Data::Dumper::Varname     = 'Hash';
$Data::Dumper::Quotekeys   = true;

$Hash->{'One'} = 1;
$Hash->{'Two'} = 2;
$Hash->{'Three'} = 3;
$Hash->{'String'} = 'Foo Bar';

print __LINE__ . ":Main:\$Hash:\n" . Dumper($Hash);
for (my $i = 0; $i < 10; $i++)
   {
   FillHashOne($i, "Value:\[$i\]");
   }
$Hash->{'HashOne'} = FillHashOne(undef());
print __LINE__ . ":Main:\$Hash:\n" . Dumper($Hash);
[download]

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