#!/usr/bin/perl
                                                                      
+                    
use warnings;
use strict;
                                                                      
+                   
use Symbol;
                                                                      
+                   
our $f1;
$f1 = gensym;
tie *$f1, 'TieTest';
<$f1>;
                                                                      
+                    
package TieTest;
                                                                      
+                    
sub TIEHANDLE
{
  my $class = shift;
  my $obj = { };
  bless $obj, $class;
  warn "TIEHANDLE: $obj\n";
  $obj;
}
                                                                      
+                    
sub READLINE
{
  warn "READLINE\n";
  return "line\n";
}
[download]

TIEHANDLE: TieTest=HASH(0x80fcb38)
Use of uninitialized value in <HANDLE> at tietest.pl line 11.
readline() on unopened filehandle at tietest.pl line 11.