in reply to Re: Making Data::Dumper also displaying (stringified) Ref-ID's?
in thread Making Data::Dumper also displaying (stringified) Ref-ID's?

Thanx toolic, indeed I have to read this thoroughly.

I was actually looking for a way to display the difference between deep and flat copy to a newbie, and no figured out that the Seen-Mechanism in Data::Dumper already reveals it, without the need to print the Ref-IDs. 8)

  DB<90> $hr2={%$hr1}  # shallow copy
 
  DB<91>  print Data::Dumper->Dump([$hr1,$hr2],[qw/hr1 hr2/])
$hr1 = {
         'a' => {
                  'b' => {
                           'c' => 1
                         }
                }
       };
$hr2 = {
         'a' => $hr1->{'a'}
       };
 
  DB<92> x $hr1,$hr2
0  HASH(0x8b64b78)
   'a' => HASH(0x8b64c18)
      'b' => HASH(0x8af9120)
         'c' => 1
1  HASH(0x8b156c0)
   'a' => HASH(0x8b64c18)
      -> REUSED_ADDRESS

[download]

Anyway IMHO an option to add the IDs as comments would be welcomed by many people as a valuable feature!

(update: maybe this can be done with Data::Dump::Streamer?)

Cheers Rolf

UDPATE: improved code example

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Re^3: Making Data::Dumper also displaying (stringified) Ref-ID's?
by ikegami (Patriarch) on Sep 27, 2009 at 00:28 UTC
    Dump the original and the copy using one call to Dumper, and the difference between a shallow and a deep copy will be obvious. 
    use Storable     qw( dclone );
use Data::Dumper qw( Dumper );

my %hash = (a=>{b=>{c=>1}});

my %shallow = %hash;
my %deep    = %{ dclone(\%hash) };

local $Data::Dumper::Indent = 1;

print("Shallow\n");
print("-------\n");
print(Dumper(\%hash, \%shallow));

print("\n\n");

print("Deep\n");
print("----\n");
print(Dumper(\%hash, \%deep));

    [download]
    Shallow
-------
$VAR1 = {
  'a' => {
    'b' => {
      'c' => 1
    }
  }
};
$VAR2 = {
  'a' => $VAR1->{'a'}
};


Deep
----
$VAR1 = {
  'a' => {
    'b' => {
      'c' => 1
    }
  }
};
$VAR2 = {
  'a' => {
    'b' => {
      'c' => 1
    }
  }
};

    [download]

    As you can see, the shallow copy clearly references back to the original, whereas the deep copy doesn't.

[reply]
[d/l]
[select]
      Thx, but what's the difference to the code in the post you're replying to?

      IMHO it's essentially the same code!(?)

      Cheers Rolf

[reply]
        I didn't notice the call to Data::Dumper. I thought the dump was actually initialisation for the subsequently demonstrated debugger solution.
[reply]

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