ZEND_FETCH_RESOURCE mystery

Hello, i'm trying to use ZEND_FETCH_RESOURCE so I can use macros instead of other stuff, but i can't figure out how to use it. I have the following php code: $blah = new Blah(); $blah->doSomething(); When Blah() is called, I want to create a structure and store it as a resource: typedef struct { int zoo; long blurb; } blah_struct; blah_struct *blah; I register my resource: ZEND_REGISTER_RESOURCE(result_returned, &blah, le_blahresource); In "doSomething" I want to get my resource back, so I try to do: ZEND_FETCH_RESOURCE(blah, blah_struct *, ????????, "blah", le_blahresource); This 3rd parameter is a mystery. I checked other modules, and they pass a zval taken from user input, but in my case, I don't have user input, I just want to get my structure back. What am I supposed to pass as the 3rd parameter?? I tried passing a reference to the Blah() object, but that didn't work. I found a workaround, using zend_list_insert and zend_list_find, but I guess I should be able to use ZEND_REGISTER and ZEND_FETCH, no? Fab.