The problem is that you are using a reference as index in an array.

I admit that this appears to be whats going on, But I do not understand how. I see no lookup of an array in that code.

Heres some toying I did with the problem.

#!perl -l
use strict;
use warnings;

my $a = {child1 => [ {child2 => [ {child3 => [ {child4 => [1]} ]} ]} ]
+};
print $a->{child1}{child2}{child3}; #cut off {child3} and no problem.

print '$a:',ref $a;
print '$a->{child1}:',ref $a->{child1};
print '$a->{child1}{child2}:',ref $a->{child1}{child2};
print '@{$a->{child1}}:',scalar @{$a->{child1}};
__END__
$a:HASH
$a->{child1}:ARRAY
$a->{child1}{child2}:HASH
@{$a->{child1}}:28004977
[download]

So it would appear that somehow $a->{child1}{child2} is being treated as an array lookup. But how? There is no array lookup involved.

Id be interested to hear an explanation as to why this isnt a bug in perl.

Pseudo-hashes are an experimental and soon-to-be-deprecated feature.

Aha! Thanks very much. It wasn't obvious to me that this was a pseudo-hash lookup, but now that you point it out its quite clear. And from this example alone its a Good Thing that they are going to go away. Any array containing a hash as the 0 element gets magically treated as a pseudo hash. The fog clears....

At the very least the pseudo-hash code should insist that the hash is composed of ONLY integer values, and certianly should NOT silently numerify the array ref. It should throw a fatal error there IMO. Anyway, we all know thats not going to happen, as they well be disappearing soon enough, but what an oversight.

*sigh* and thanks. Good eye.


---
demerphq



First they ignore you, then they laugh at you, then they fight you, then you win.
-- Gandhi

The problem is that you are using a reference as index in an array.

How so? You can certainly see the effect with the attempt to access the first non existent key (but only on Linux) but could you explain that further.....

C:\>type test.pl
use Data::Dumper;

my $a={ child1 => [ {child2 => [ { child3 => [ {child4 => [ 1 ] } ] } 
+] } ] }; 
print Dumper $a;
print Dumper $a->{child1};
print Dumper $a->{child1}{child2};
print Dumper $a->{child1}{child2}{child3};
print Dumper $a->{child1}{child2}{child3}{child4};

C:\>perl test.pl
$VAR1 = {
          'child1' => [
                        {
                          'child2' => [
                                        {
                                          'child3' => [
                                                        {
                                                          'child4' => 
+[
                                                                      
+  1
                                                                      
+]
                                                        }
                                                      ]
                                        }
                                      ]
                        }
                      ]
        };
$VAR1 = [
          {
            'child2' => [
                          {
                            'child3' => [
                                          {
                                            'child4' => [
                                                          1
                                                        ]
                                          }
                                        ]
                          }
                        ]
          }
        ];
$VAR1 = undef;
$VAR1 = undef;
$VAR1 = undef;

C:\>

[root@devel3 root]# cat test.pl
use Data::Dumper;

my $a={ child1 => [ {child2 => [ { child3 => [ {child4 => [ 1 ] } ] } 
+] } ] }; 
print Dumper $a;
print Dumper $a->{child1};
print Dumper $a->{child1}{child2};
print Dumper $a->{child1}{child2}{child3};
print Dumper $a->{child1}{child2}{child3}{child4};
[root@devel3 root]# perl test.pl
$VAR1 = {
          'child1' => [
                        {
                          'child2' => [
                                        {
                                          'child3' => [
                                                        {
                                                          'child4' => 
+[
                                                                      
+  1
                                                                      
+]
                                                        }
                                                      ]
                                        }
                                      ]
                        }
                      ]
        };
$VAR1 = [
          {
            'child2' => [
                          {
                            'child3' => [
                                          {
                                            'child4' => [
                                                          1
                                                        ]
                                          }
                                        ]
                          }
                        ]
          }
        ];
$VAR1 = undef;   # hangs for 5 seconds here
$VAR1 = undef;
$VAR1 = undef;
[root@devel3 root]#
[download]

cheers

tachyon

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