EDIT: 

After reading the responses to my post, I've come to two tentative conclusions: 1) I have only a loose grasp of how references work in Perl. It's obvious I have a lot to learn on the subject. 2) In this case, I'm mistaking output for content (Data::Dumper does not represent the reference structure's content in the way I imagined). 3) This is frustrating but fun as hell.



Here's my edited code that gives me what I want (thank you all for helping me with this):


sub inc{
   my $ref=shift;
   my $span=shift;
   $span?($span--):($span=1);

   my @b=map{ clone([@$ref[$_-$span..$_]])  }($span..$#$ref);

   \@b
}
sub clone{#clone references
   my $ref=shift;
   my@array=map{ ref($_)?clone($_):$_ }@$ref;
   \@array
}
my@b=(1..5);
my $c = inc(inc(\@b));
print Dumper $c;

[download]


Which produces:

$VAR1 = [
          [
            [
              1,
              2
            ],
            [
              2,
              3
            ]
          ],
          [
            [
              2,
              3
            ],
            [
              3,
              4
            ]
          ],
          [
            [
              3,
              4
            ],
            [
              4,
              5
            ]
          ]
        ];

[download]


Woohoo!


ORIGINAL POST:


I have come across a strange thing. If I run the following code with an array of scalars, then I get what I expect. E.g.,

@a = (1,2,3,4,5,6);
increment(\@a);

#produces tuples of:
[1,2],[2,3],[3,4],[4,5],[5,6] #yay!!

[download]


But, I want to run increment() with arrays of arrays. But, the result is all sorts of funky.
Here's Data::Dumper output:


$VAR1 = [
          [
            [
              1,
              2
            ],
            [
              2,
              3
            ]
          ],
          [
            $VAR1->[0][1],
            [
              3,
              4
            ]
          ],
          [
            $VAR1->[1][1],
            [
              4,
              6
            ]
          ]
        ];

[download]



I'm using the following test code:


my @a = (1,2,3,4,6);

print Dumper increment(increment(\@a));

sub increment{
   my $d=shift;
   my @b;
   for my $i (1..$#$d){
      my @a = @$d[$i-1..$i];
      push @b,\@a;
   }
   \@b
}

[download]



The output is half-right --the second part of each tuple is itself a tuple (and is what's expected). But, what's with the first part of each tupple? The "$VAR->[n][1]"



I am flummoxed.



Thanks much for whatever advice you might have.






$state{tired}?sleep(40):eat($food);

 
 


In reply to Array of Arrays: why is "$VAR1->[0][1]" and the like embedded within?
by corenth





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