Call to undefined function cache_get()

When debugging with Zend Studio, you may get the fatal error "Call to undefined function cache_get()" when debugging, even though your site appears just fine in the browser.

Zend Studio seems to search open files first without regard to their actual paths. In my case, I had the file from the views module open in Zend, and Zend was loading that instead of includes/ during debugging. Simply closing the file solved the problem.