Re: Extracting values from nested hashrefs

[choroba]

I am not sure whether map plus double values counts as implicit traversing:

say for map values %$_, values %$animals;

Update: simplified.

[loris]

Ah, sorry, my example was too simple. It should have been like this:

my $animals = {
               gnu => {
                       humps => 0,
                       mascot_for => 'emacs',
                      },
               dromedary => {
                             humps => 1,
                             mascot_for => 'perl',
                            },
               camel => {
                         humps => 2,
                         mascot_for => 'perl',
                        },
              };

BTW, implicit traversing is OK; I just wanted to avoid some sort of loop with , say while.

Thanks,

loris

[choroba]

You can use

map $_->{humps}, values %$animals;

If your structure becomes even more complicated (e.g. different level of nesting), you should use recursion (or CPAN).

[Athanasius]

Here is an approach that should work no matter how complicated your data structure becomes (provided the data you want remains in the form humps => d):

#! perl
use strict;
use warnings;
use Data::Dumper;

my $animals = {
                 gnu       => {
                                 humps      =>  0,
                                 mascot_for => 'emacs',
                              },
                 dromedary => {
                                 humps      =>  1,
                                 mascot_for => 'perl',
                              },
                 camel     => {
                                 humps      =>  2,
                                 mascot_for => 'perl',
                              },
              };

my $flat = Dumper($animals);
print "$1\n" while $flat =~ / 'humps' \s+ => \s+ (\d+) /gx;

Output:

2
0
1

TMTOWTDI.