Traversing a multi-dimensional hash in Perl

Question

If you have a hash (or reference to a hash) in perl with many dimensions and you want to iterate across all values, what\'s the best way to do it. In other words, if we hav

Answer 1

Keep in mind that Perl lists and hashes do not have dimensions and so cannot be multidimensional. What you can have is a hash item that is set to reference another hash or list. This can be used to create fake multidimensional structures.

Once you realize this, things become easy. For example:

sub f($) {
  my $x = shift;
  if( ref $x eq 'HASH' ) {
    foreach( values %$x ) {
      f($_);
    }
  } elsif( ref $x eq 'ARRAY' ) {
    foreach( @$x ) {
      f($_);
    }
  }
}

Add whatever else needs to be done besides traversing the structure, of course.

One nifty way to do what you need is to pass a code reference to be called from inside f. By using sub prototyping you could even make the calls look like Perl's grep and map functions.