How can I tell if a class is defined?

ou can do it this way:

if(!defined("__PREPEND_INCLUDE_INC__"))
include("$DOCUMENT_ROOT/php3/phplib6/prepend.php3");

and in prepend.php3, I begin with

if(!defined("__PREPEND_INCLUDE_INC__"))
define("__PREPEND_INCLUDE_INC__",1);



Nice way, but you need to manage your includes with an if-statement. An
alternative solution may be

prepend.php3:

if(!defined("__PREPEND_INCLUDE_INC__")) {
define("__PREPEND_INCLUDE_INC__",1);

// your code

}

So you can leave your include simple.