In my CGI.pm, that passage reads,
You can set up a callback that will be called whenever a
file upload is being read during the form processing. This
is much like the UPLOAD_HOOK facility available in
Apache::Request, with the exception that the first
argument to the callback is an Apache::Upload object, here
it's the remote filename.
$q = CGI->new();
$q->upload_hook(\&hook,$data);
sub hook
{
my ($filename, $buffer, $bytes_read, $data) = @_;
print "Read $bytes_read bytes of $filename\n";
}
The hook is not an argument to
new, but is set in the
upload_hook method.