Yesterday I wanted to compare two hashes to see if they were the same. I looked around a little bit and found Data::Compare. It was good at telling me the two hashes were different, however, it did not tell me where. So, I wrote a small little subroutine to recursively check my hash of hashes (of hashes). It was able to identity where I had to look to make corrections, almost to the exact spot. (I am unsure how to compare arrays of hashes just yet which is why the following little subroutine will almost take you to the right spot.)

There are still holes in the script, but it worked for me today.

#!/usr/bin/perl
use strict;
use warnings FATAL => qw( all );

use Data::Compare;
use Data::Dumper;

# You can take out all instances of the subroutine 'line' to print wha
+t you want in those places.

sub deep_data_compare {
  my ($tab, $old_data, $new_data, $data) = @_;

  my $old = $old_data;
  my $new = $new_data;

  my $compare = new Data::Compare($old, $new);

  if ($compare->Cmp == 0) {
    line($tab,$data) if $data;
    
    if (ref($old) eq 'HASH' && ref($new) eq 'HASH') {
      line($tab+1,'old to new');
      for (keys %$old) {
        deep_data_compare($tab+2,$_,$$old{$_},$$new{$_});
      }
    }

# I have not figured out this part yet.
#    elsif (ref($old) eq 'ARRAY' && ref($new) eq 'ARRAY') {
#    }

    else {
      print Dumper($new);
      print Dumper($old);
    }
  }
}

sub rline {
  my ($tab,$line) = @_;
  return qq(\t) x $tab.qq($line\n);
}

sub line {
  print rline(@_);
}


deep_data_compare(0, \%old_hash, \%new_hash, 'widgets');

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No matter how hysterical I get, my problems are not time sensitive. So, relax, have a cookie, and a very nice day!
Lady Aleena

In reply to Using Data::Compare recursively to better identity differences between hashes by Lady_Aleena

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