Protecting the user (devloper) from themselves ?

as part of an extension i'm working on, im implementing support for an iCal compliant RecurrenceRule class. to make it play nice in PHP5, i want to add an iterator, to loop through all the occurrences specified by the rule. so for instance /* DTSTART ommitted, but supported */ $payday = new RecurrenceRule("FREQ=MONTHLY;BYMONTHDAY=1,15;BYHOUR=12;COUNT=10;"); foreach($payday as $date) { echo prettify($date) . '\n'; } so far so good, right ? except the base calculation engine supports dates of about 140742BC to 144683AD. now imagine the rule FREQ=SECONDLY but i guess theres also nothing stopping someone from doing while (0) {}; if i go ahead with this, is there a way from the iterator code to periodically check for script timeout ? l0t3k