I, like other responders, like to pass hash *references* as opposed to hashes. This comes in handy especially when you want to pass other things, as well as a hash, as arguments to a subroutine. Hashes and arrays get flattened out into one long string of scalar parameters, so if you stick to passing scalars (like hash references) around, you'll never have problems :-)

Here's a snippet from 'perldoc perlsub':

       The Perl model for function call and return values is simple: a
+ll func-
       tions are passed as parameters one single flat list of scalars,
+ and all
       functions likewise return to their caller one single flat list 
+of
       scalars.  Any arrays or hashes in these call and return lists w
+ill col-
       lapse, losing their identities--but you may always use pass-by-
+refer-
       ence instead to avoid this.  Both call and return lists may con
+tain as
       many or as few scalar elements as you’d like.  (Often a functio
+n with-
       out an explicit return statement is called a subroutine, but th
+ere’s
       really no difference from Perl’s perspective.)
[download]

If you instead pass parameters like this:

   sub print_person {
      my $address_hashref = shift;
      my $hobbies_arrayref = shift;
      print "address line 1 = $address_hashref->{'addr1'}\n";
      print "address line 2 = $address_hashref->{'addr2'}\n";
      # etc, etc.
 
      # or, turn hashref back into a hash, and arrayref back  into an 
+array
      my %address = %{$address_hashref};
      my @hobbies = @{$hobbies_arrayref};
      print "address line 1 = $address{'addr1'}\n";
   }

   my %address = (
      "addr1" => "1 Main St",
      "addr2" => "Suite 101",
      "city"  => "Somecity",
      "state" => "Somestate"
   );
   my @hobbies = ( "flying", "mountain climbing" );

   print_person(\%address, \@hobbies);
[download]

HTH.