How to create nesting hashes given the innermost value and an array of keys?

[EchoAngel]

E.g. given the array @a = qw/foo bar burp/ and the value 1, create a hash like

%h = (
      'foo' => {
                 'bar' => {
                            'burp' => 1
                          }
               }
      );

Originally posted as a Categorized Question.

[Roy Johnson]

Recursively walk a hash to get to an element

[niggles]

Input in @a, output in $last[-1].

use Data::Dumper;
$Data::Dumper::Deepcopy = 1;

my @a = qw/foo bar baz/;
my @last = (1);
push @last, { $_ => $last[-1] } foreach reverse @a;
print Dumper( $last[-1] ); # result

I use Data::Dumper just to print the output. It is not required to obtain the result. Output:

$VAR1 = {
          'foo' => {
                     'bar' => {
                                'baz' => 1
                              }
                   }
        };

[codeacrobat]

Why do it so complicated?

%hash = map{($_, $value)} @array;

Originally posted as a Categorized Answer.

[EchoAngel]

This functiontakes elements in an array and builds them into keys for a hash:

#  Usage: UsesArrayElementsAsKeyElementsInHash( \%hash, $value, @array
+ )
use Carp;
sub UsesArrayElementsAsKeyElementsInHash
{
  my $hash = my $root = ( ref $_[0] ? shift : {} );
  my $value = shift;
  my $last = pop;

  for my $key ( @_ )
  {
    $hash = ( $hash->{$key} ||= {} );
    ref $hash or croak "key = $key\n";
  }
  $hash->{$last} = $value;
  return $root;
}