use IO::File;

$var = <<EOT;
line 1
line 2
line 3
EOT

###open($fh, '<', \$var) || die $!; # this works #
$fh = IO::File->new('<', \$var) || die $!; # but this does not #
while ($line = $fh->getline()) {
   print $line;
}
$fh->close();