Unexpected Data::Dumper results

[tqisjim]

Here is some output from Data::Dumper:

$VAR1 = {
          'shared' => \'true',
          'parents' => [
                         {
                           'isRoot' => $VAR1->{'shared'}
                         }
                       ]
        };

Naturally, this looks like executable perl code. But it doesn't work. Upon evaluation:

  $VAR1->{parents}->[0]->{isRoot} == undef

It's clear why the results are what they are. But I'm surprised that such a ubiquitous utility would have such a fundamental shortcoming. I'm trying to use this forum to publicize some of my recent distros. And this discovery is coupled with bugs due to my blind reliance on Data::Dumper.

I'm struggling to incorporate some elegant workaround, and counting on the probability that someone has effectively dealt with this problem already.

Any thoughts or meditations? -Thanks!

-Jim

[choroba]

Before dumping the original value, you should have set

$Data::Dumper::Purity = 1;

It leads to the following output:

$VAR1 = {
          'shared' => \'true',
          'parents' => [
                         {
                           'isRoot' => do{my $o}
                         }
                       ]
        };
$VAR1->{'parents'}[0]{'isRoot'} = $VAR1->{'shared'};

[tqisjim]

Thanks! Just what I needed!

[hdb]

Probably not what you would call elegant but if you execute it twice, it works... at least in this case. Just like LaTeX...

$VAR1 = {
          'shared' => \'true',
          'parents' => [
                         {
                           'isRoot' => $VAR1->{'shared'}
                         }
                       ]
        } for (1..2);
print $VAR1->{parents}->[0]->{isRoot},"\n";

[tqisjim]

Executing twice seems like the obvious solution... but there's some loss of data integrity.

[hdb]

...and, as with LaTeX, there might be situations where two runs are not enough...

[DrHyde]

I see that others have shown you how to work around this particular problem, but I recommend that in the general case you use Data::Dump::Streamer's DumpLex function, and install PadWalker so that it can work all its magic.