Perl - pass by reference v pass by value

In the old days when I was a programmer in a long forgotten language
(Coral-66) it was really clear if you were using a value or a
reference/location when working with stuff.

I have just been caught out with this in Perl and would like to know the
correct way to make the setting of variable $newvalue below to be a
value and not a reference.

Here is example code:

Code:
--------------------
    
  use Data::Dumper;
  my $dumped;
  
  my $variable1 = {
  subarray => ['abc1', 'abc2']
  };
  
  
  $dumped = Dumper $variable1;
  print "Original: $dumped\n";
  
  foreach my $newvalue ( @{$variable1->{subarray}} ){
  print "subarray value: $newvalue\n";
  $newvalue = 'a new string';
  }
  
  $dumped = Dumper $variable1;
  print "Original has been changed: $dumped\n";
  
--------------------


and here is the output

Code:
--------------------
    
  Original: $VAR1 = {
  'subarray' => [
  'abc1',
  'abc2'
  ]
  };
  
  subarray value: abc1
  subarray value: abc2
  Original has been changed: $VAR1 = {
  'subarray' => [
  'a new string',
  'a new string'
  ]
  };
  
--------------------


I did not expect that the values in $variable1 to change through me
changing a new local variable $newvalue.



Paul Webster
http://dabdig.blogspot.com
author of \"now playing\" plugins covering radio france (fip etc),
planetradio (bauer - kiss, absolute, scala, jazzfm etc), kcrw, supla
finland, abc australia, cbc/radio-canada and rte ireland
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