MFC throws pointers, Xerces throws various types not derived from std::exception, and as I recall the Lotus Notes API throws integers. An interesting diversity. But as the Chinese curse goes: may you live in interesting times! Such non-standard exceptions generally require you to have multiple catches every place such an exception could otherwise escape to higher levels, or where you want to handle any exception with a given general meaning. It’s not that the designers have tried to be clever or that they’re out to get you: it’s just that these libraries stem from before C++ was standardized, i.e., before 1998.
One partial remedy is exception translation. Somehow arrange for any non-standard exception to be caught and result in some corresponding exception derived from std::exception. It does not solve all the problems – but it sure beats doing it by copy-n’-paste coding of exception handlers!
With C++98 exception translation cannot be completely centralized in a portable, reusable way. As far as I know that’s not possible even with the upcoming C++0x standard. But it’s possible to provide portable and application-independent support that does most of the job, and that provides a general convention that largely eliminates the chance of any non-standard exception slipping through, and that’s what I discuss here. [… More] Read all of this posting →
Alf on programming (mostly C++) 