http://www.perlmonks.org?node_id=535575


in reply to unknown number of dimensions of a multidimensional hash

If the hash is not ragged, you simply know its dimensionality. If you somehow lose this information

sub hashfirst { $_[0]->{($_) = keys %{$_[0]}} }
sub shape {
  my $h = shift;
  my @s;
  for (;'HASH' ne ref $h; $h = hashfirst($h)) {
    push @s, scalar(keys %$h);
  }
  @s
}

[download]

may help you remember. This feels like an X-Y question.

In Section Seekers of Perl Wisdom