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NOTE: use Perl; is on undef hiatus. You can read content, but you can't post it. More info will be forthcoming forthcomingly.

All the Perl that's Practical to Extract and Report

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  • Well, go ahead and do this with eval if you're not concerned with either speed or security.

    Eval means you're firing up the compiler. Fun fun. Slow slow.

    Eval also means that you have to be very careful about the data. It'd be trivial to launch arbitrary code by selecting the proper data here.

    There's really no need. You can run a lot faster and a lot safer with:

    $tree ||= {};
    my $place = $tree;
    $place = $place->{$_} ||= {} for split /:/, $path;
    (This may not be precisely the code, but this seemed to handle the cases I ran it on.)

    Also note that in your version, first following "A::B" then "A::B::C" means you were storing data into %1 symbolically (disabled with "use strict"). Bad.

    --
    • Randal L. Schwartz
    • Stonehenge
    • $tree ||= {};
      my $place = $tree;
      $place = $place->{$_} ||= {} for split /:/, $path;

      Something like that lets you end with a HASHref instead of the SCALARref. Unfortunately, you can't create a reference to a hash element's value part.

      But adding something like a _value key solves that:

      sub walk_tree {
          my ($hashref, @path) = @_;
          $hashref = \%{ $hashref->{$_} } for @path;
          return $hashref;
      }
       
      my $tree = {};
      ${ walk_tree $tree => qw(A B C) }{_value} = "value";