Can I put include or require inside a class definition?

No.

You just can't put anything inside a class definition EXCEPT variable
and function definitions.

The following code is *not* legal:

<?
class Database {

/* properties */
var $db_path;
var $db_id;
var $db_fields;

/* Services */
require("open.inc");
require("close.inc");

}
?>


To clarify, the following code *does* work. This because all we have in
the class are variable and function definitions; the require() is inside
the function definition for open().