Perl: best way to pass array of hash to a sub - arrays

Question

My class looks like the below:
package CSVKeepCols;
use strict;
use warnings;
use Text::CSV;
use Data::Dumper;
my $text;
my $del;
my #cols;
my $output = '';
sub load {
my $class = shift;
my $self = {};
bless $self;
return $self;
}
sub input {
my $class = shift;
$text = shift;
return $class;
}
sub setOpts {
my ($class, $opts) = #_;
$del = $opts->{'delimeter'};
#cols = $opts->{'columns'};
}
sub process {
my #lines = split /\n|\r|\n\r|\r\n/, $text;
my $csv = Text::CSV->new({ sep_char => $del });
foreach (#lines) {
die('Invalid CSV data') if !$csv->parse($_);
$output .= __filterFields($csv->fields()) . "\n";
}
}
sub output {
return $output;
}
sub __filterFields {
my #fields = #_;
my $line = '';
foreach (#cols) {
$line .= ',' if $line;
$line .= $fields[$_];
}
return $line;
}
1;
I am using this class from my code like this:
$parser = load CSVKeepCols();
$parser->input($out);
$parser->setOpts({'delimeter' => ',', 'columns' => [1,2]});
$parser->process();
$out = $parser->output();
I am expecting, the setOpts subroutine will take the hash {'delimeter' => ',', 'columns' => [1,2]} and from there it will set the value of $delto , and #cols to (1,2) so that I can loop through the #cols array.
However, when I try to loop through #cols in the __filterFields subroutine I get error
Use of reference "ARRAY(0x22e32e0)" as array index at CSVKeepCols.pm line 52.
How do I fix this?

Answer 1

In setOpts, you set #cols = $opts->{columns};
$opts->{columns} contains a reference to an array ( [1,2] ).
So in __filterFields:
for ( #cols ){
# $_ is an arrayref [1,2]
# you are using it as an index to retrieve a value from #fields
$line .= $fields[$_];
# Thus the error: "use of reference ARRAY"..." as array index"
# You should be using an integer here.
}
To fix it:
sub setOpts {
# ...
#cols = #{ $opts->{columns} };
}
Edit: removed unnecessary check