On 8/31/10 2:11 PM, Ed Leafe wrote: > On Aug 31, 2010, at 4:27 PM, Paul McNett wrote: > >> Well, there could be infinite recursion, which I guess would then be a kind >> of >> infinite loop. > > Yes, which is an example of misusing it. Recursion is for finite, > tree-like structures. No algorithm handles infinite loops particular well, > for that matter.
I agree, by the way, with using recursion for tree traversal. But you may have to put checks in your recursive function to catch possible infinite recursion: obj .id = 23 .parent_id = 21 .child_ids = (42, 64, 921) obj .id = 42 .parent_id = 23 .child_ids = (23, 42) Obviously, objects in a tree should never be children of themselves, etc., but maybe something erroneously set it up that way and now we need to deal. Depending on your needs you may not need to do the check, but just catch your programming language's MaximumRecursionDepthExceeded exception and ignore or log the failing node. The recursive function may not expect an infinitely recursive case, yet one may still come to it in the tree data. So in some sense your function will at least have to deal with the possibility of infinitely-recursive cases. Obviously, you are aware of all this, but it wouldn't be fair to blame the programmer of the recursive function of misusing recursion if an infinite-loop-infested tree were thrown at it one day. Recursion is awesome. Powerful and simple. But once you add checks in them to deal with edge-cases, recursive functions can get unwieldy pretty quickly. With great power comes great responsibility I guess! Paul _______________________________________________ Post Messages to: [email protected] Subscription Maintenance: http://leafe.com/mailman/listinfo/profox OT-free version of this list: http://leafe.com/mailman/listinfo/profoxtech Searchable Archive: http://leafe.com/archives/search/profox This message: http://leafe.com/archives/byMID/profox/[email protected] ** All postings, unless explicitly stated otherwise, are the opinions of the author, and do not constitute legal or medical advice. This statement is added to the messages for those lawyers who are too stupid to see the obvious.
