Hello Monks, I am trying to create a hash, pass that hash as an argument to a subroutine, and then after returning from that subroutine, keep any of the changes that might have been made by that hash. Here is my code:

#!/usr/bin/perl

use strict;
use warnings;

use Data::Dumper;

my %records = ();
my $ref = \%records;

print "Before call to DoStuff\n";
print "Hash reference: '$ref'\n";
print Dumper(\%records);
DoStuff(\%records);
print "Back from call to DoStuff\n";
print Dumper(\%records);
exit(0);

sub DoStuff
{
  my $hash_ref = shift;
  print("In DoStuff: ");
  print "Hash reference: '$hash_ref'\n";
  my %temp_records = %{ $hash_ref };
  $temp_records{"foo"} = "bar";
  print Dumper(\%temp_records);
  return;
}
[download]

And here is the output:

Before call to DoStuff

Hash reference: 'HASH(0x1da6e78)'

$VAR1 = {};

In DoStuff:
Hash reference: 'HASH(0x1da6e78)'

$VAR1 = {
          'foo' => 'bar'
        };

Back from call to DoStuff

$VAR1 = {};
[download]

After the call to DoStuff(), why is the "foo" key gone? How do I fix this?

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