perl: naming hash variables read from YAML - perl

Question

I'm reading some information from a YAML file
groceries.yaml
# comment
fruit:
apples: 1
oranges: 1
grapes: 1
vegetables:
potatoes: 1
onions: 1
leeks: 1
into a perl script
myscript.pl
#!/usr/bin/perl
use strict;
use warnings;
use YAML::Tiny;
# Create a YAML file
my $stuff = YAML::Tiny->new;
# Open the config
$stuff = YAML::Tiny->read( 'groceries.yaml' );
print "Fruit: ", %{($stuff->[0]->{fruit})},"\n";
print "Vegetables: ", %{($stuff->[0]->{vegetables})},"\n";
exit
This works fine, but I would like to have one hash for fruit and one for vegetables. My naive attempt was
my #keys = keys %{($stuff->[0])};
foreach my $key (#keys){
my %{ $key } = %{($stuff->[0]->{$key})},"\n";
}
but clearly this doesn't work.
I'd love to understand what I'm doing wrong, and am open to different work flows that accomplish the same idea :)

Answer 1

Try this :
#!/usr/bin/perl
use strict;
use warnings;
use YAML::Tiny;
use Data::Dumper;
# Create a YAML file
my $stuff = YAML::Tiny->new;
# Open the config
$stuff = YAML::Tiny->read( 'groceries.yaml' );
my %fruits = %{ $stuff->[0]->{fruit} };
my %vegetables = %{ $stuff->[0]->{vegetables} };
I don't know why you put some parentheses in your code :
%{($stuff->[0]->{$key})},"\n";
I think this is the problem.
To iterate over the HASHes,
use Data::Dumper;
# ...
foreach my $key (keys %{ $stuff->[0] }) {
print Dumper $stuff->[0]->{$key};
}
Edit2
#!/usr/bin/perl
use strict;
use warnings;
use YAML::Tiny;
use Data::Dumper;
# Create a YAML file
my $stuff = YAML::Tiny->new;
# Open the config
$stuff = YAML::Tiny->read( 'groceries.yaml' );
my %top_h;
foreach my $key (keys %{ $stuff->[0] }) {
$top_h{$key} = $stuff->[0]->{$key};
}
print Dumper \%top_h;

Answer 2

This solution enables you to access %fruit and %vegetables. They are declared as package global variables using our so that they will be in the symbol table, which then allows you to do use symbolic references or glob assignments. You'll also need to turn off strict refs to enable this. Also see this reference.
use strict;
use warnings;
use YAML::Tiny;
use Data::Dumper;
my $stuff = YAML::Tiny->read('groceries.yml');
my %groceries = %{$stuff->[0]};
our %fruit;
our %vegetables;
{
no strict 'refs';
#no strict 'vars'; # don't need above 'our' declarations with this
while (my ($key, $val) = each %groceries) {
%$key = %$val;
# or *$key = $val;
}
}
print Dumper \%fruit;
If you don't know the keys upfront, then you'll also need to turn off strict vars so you don't need to declare the hashes before assigning to them. But then you might get a warning when you use the hash directly.
But having said all of that, I think it would be simplest to just use %groceries.

Answer 3

my ( $fruit, $vegetables) = #{$stuff->[0]}{ qw<fruit vegetables> };
If you want to do this in a loop, first, I would save the first "document" to a local reference.
my $yaml = $stuff->[0];
And then in a while loop, do this:
while ( my ( $k, $v ) = each %$yaml ) {
say ucfirst( $k ) . ': ' . %$v;
}
You could also use List::Pairwise and do this:
mapp { say ucfirst( $a ) . ': ' . %$b } %{ $stuff->[0] };