on Thu Sep 13 2007, Howard Hinnant <hinnant-AT-twcny.rr.com> wrote:
Hello,
I am requesting comments, both for and against a "sticky exception". A sticky exception is one in which once thrown, is very hard to catch and handle, without an implicit rethrow. This represents some condition which the thrower believes is sufficiently severe that the application (or thread) should clean up resources, but not be allowed to continue, even with a catch (...) which does not rethrow.
The only purpose I have ever heard for such a thing would be to handle programming and critical data integrity errors (which in practice are due to programming errors). Exeptions are for *recoverable* conditions. I'm strongly against a sticky exception unless there's a way to label particular cleanups as "critical" and have only those executed when a sticky exception is thrown. Most cleanups are noncritical, and in the presence of integrity problems, can cause problems and interfere with the critical recovery actions that you really do want to execute. Furthermore, it tends to reinforce the misconception that exceptions are a good way to handle nonrecoverable conditions. Frankly there are probably better ways to handle this than by throwing a special exception. Critical cleanups could be registered/unregistered as atexit() actions. Did I mention recently that turning a logic error into an exception is a bad idea (http://tinyurl.com/2ph58t) and we have no programming model for handling it? -- Dave Abrahams Boost Consulting http://www.boost-consulting.com The Astoria Seminar ==> http://www.astoriaseminar.com