Using a hash as a reference is deprecated

Question

I have a problem with a Perl script but don't know why. I have something like this

..
$ref = pfget($Pf, "criteria");
%criteria= %$ref;
..
..
foreach $key (keys %criteria) {
  $expr = %criteria->{$key};
  ..
}

The line $expr = %criteria->{$key} gives me an error

Using a hash as a reference is deprecated

I've tried $expr = $criteria{$key} but the script is not working as it should be.

Have you got any idea where I am going wrong?

Answer 1

%criteria in scalar context is suppose to return statistics about the hash.

$ perl -E'my %h = ( a=>1, b=>2, c=>3 ); say scalar %h'
3/8

So

%criteria->{$key}

means

"3/8"->{$key}

But a bug in Perl causes it to behave as

(\%criteria)->{$key}

The warning is telling you that your code is buggy because your code is relying on a bug in Perl. Use

$criteria{$key}

or avoid the wastefulness of creating %criteria and use

for my $key (keys %$ref) {
   ... $ref->{$key} ...
}