On 9/15/07, Howard Hinnant <hinnant@twcny.rr.com> wrote:
On Sep 13, 2007, at 2:23 PM, Howard Hinnant wrote:
I promised to explain myself after a day or two and that time has come. Thanks much to everyone who has responded.
The application is thread cancellation. One might want to call this thread interruption or whatever. Thread interruption (I shall use the term interruption as opposed to cancellation for really no good reason) is essentially an exception. The stack gets unwound, executing "landing pads" on the way up. Those "landing pads" in C++ are destructors and catch clauses.
If ~A() is really not nothrow (even though it appears to be), then std::vector is really not going to work very well in an exceptional condition (i.e. it will leak A's). I.e. I have grave concerns over sticky_exception myself, even if its only application is thread interruption.
The other 'example' of sticky exceptions, that we all accept as valid, is throwing inside a constructor - you can't catch a base class constructor throw and handle it in the derived class' constructor. I bring that up as a somewhat related example of 'sticky' exceptions. Not that I think the thread case should necessarily follow the same idea. Tony