Restrict search results to specific pages using array variable?

Hello,

I’m restricting my search function using a filter similar to this:

function searchfilter($query) {

	    if ($query->is_search) {
	        $query->set('post_type',array('post','page'));
	    }

	return $query;
	}
	 	add_filter('pre_get_posts','searchfilter');

What I’m trying to do is limit the search to certain pages. I have the IDs of these pages stored in a global variable from a different function ($page_array), so I know I shouldn’t have to list all of the page IDs in another array, like this:

$query->set('ID', array(52, 33, 45, etc));

But I can’t figure out how to pass the $page_array variable to the filter function. I’m feeling syntactically challenged. Any assistance is greatly appreciated.