Can I put batch api callbacks in an include file? I have a .module file that is getting quite lengthy, and I added some batch functionality to it. I put the form and batch callbacks in a separate .inc file, and added the appropriate file directive to the menu array. 

I was able to get the form submission to work, but the batch api threw the error Warning: call_user_func_array() expects parameter 1 to be a valid callback, function '_my_batch_callback' not found or invalid function name in _batch_process(). I got this error until I moved the batch callbacks into the .module file. 

Is it possible to put the batch callbacks into a separate include file? Or have I just done something wrong?
Actually, there is a file directive in the batch array. I found it was necessary to include drupal_get_path to fully reference the file's path.

'file' =&gt; drupal_get_path('module', 'MY_MODULE') . '/includes/my-batch.inc'