How do I use symbolic references in Perl?

Question

In Perl, if a variable holds the name for another variable, how do I use the first variable to visit the other one?

For example, let

$name = \"bob\";         


        

Answer 1

Usually when you think you need to use symbolic references, you will be better served by using a hash (associative array).

use strict;
use warnings;

my %user = (
  'bob' => [qw' jerk perlfan '],
  'mary' => 'had a little lamb',
);

{
  for my $name (qw'bob mary susan'){
    if( exists $user{$name} ){

      if( ref($user{$name}) eq 'ARRAY' ){
        print join( ' ', @{$user{$name}} ), "\n";

      }else{
        print $name, ' ', $user{$name}, "\n";
      }

    }else{
      print "$name not found\n";
    }
  }
}

Results in:

jerk perlfan
mary had a little lamb
susan not found

If you think you really need to use symbolic references, this is a safer way to do that.

use strict;
use warnings;

# can't use my
our @bob = ("jerk", "perlfan");
our $mary = 'had a little lamb';

{
  for my $name (qw'bob mary susan'){
    if( exists $::{$name} ){
      my $ref = $::{$name};

      if( *{$ref}{ARRAY} ){
        print join(' ',@$ref), "\n";

      }elsif( *{$ref}{SCALAR} ){
        print "# $name is not an array, it's a scalar\n";
        print $name, ' ', $$ref, "\n";
      }

    }else{
      print "$name not found\n"
    }
  }
}

Which returns:

jerk perlfan
# mary is not an array, it's a scalar
mary had a little lamb
susan not found

---

You should notice that it is harder to symbolic references safely, which is why you shouldn't use them.

_{Unless of course you are an expert doing something advanced.}