A manual "goto" like link to sign a person in and redirect them to that page...?

Hi,

In my set up, I create theme files where I manually check what the user's roles are. If their roles aren't right, I don't allow them to see a certain page.

so like:

global $user;
if ($user->uid = ....) {
  //...show stuff...
}
else {
  //redirect to a login page, and that login page will redirect them back here.
}

So I know I can use drupal_goto and just redirect them to '/user/login'

But is there a special way to redirect the user to the logintoboggan screen that will, after logging in, redirect the user back to the previous page?

Thanks!