Re: Soft Array Refs

[stevieb]

Don't do it. Here's a valuable and entertaining three part story by Mark-Jason Dominus as to why doing these things should be avoided wherever possible. There are many other stories out there stating why this isn't such a good idea unless you *really* know what you're doing.

Hashes are designed for this. Here's an example. Just ask if you have questions. Usually, it's the dereferencing that confuses most people.

#!/usr/bin/perl

use strict;
use warnings;

use Data::Dumper;

my %data;
my $array_name;

while (my $line = <DATA>) {
    chomp($line);
    if ($line =~ /Array\s+(\w+)\s+(\d+)/) {
        $array_name = "table_" . $1 . "_" . $2;
        next;
    }
    my $value = (split /\s+/, $line)[1];
    push @{ $data{$array_name} }, $value;

}

print "Printing entire structure:\n";

print Dumper \%data;

print "\nPrinting all values from all arrays:\n\n";

for my $key (keys %data){
    print "in array '$key'\n";
    for my $elem (@{ $data{$key} }){
        print "$elem\n";
    }
}

print "\nPrinting values only from 'table_min_1':\n";

for my $item (@{ $data{'table_min_1'} }){
    print "$item\n";
}

__DATA__
Array max 1
useless_text_field a
useless_text_field b
useless_text_field c
Array max 2
useless_text_field 1
useless_text_field 2
useless_text_field 3
Array min 1
useless_text_field d
useless_text_field e
useless_text_field f
Array min 2
useless_text_field 4
useless_text_field 5
useless_text_field 6

-stevieb

[smknjoe]

Thanks Stevie.

I regretted posting it about 30 minutes later after I had two words for myself: "associative arrays", aka a hash.

Up to now, I've gotten by with arrays for everything but now I see a true need for using a hash.

[shawnhcorey]

Rule of thumb: If order matters, use an array; otherwise use a hash.

Most of the time, you should use a hash because of its expressive power. You can think of a hash as a miniature symbol table, if it helps. :)