Question

I’m using c++ and i’m in a really deeply nested set of functions and a special case has occurred and I would like to exit to the top level.

Now I hear c++ exceptions are deprecated now so what should I use instead in this case?

So what i’m really asking is, are setjmp() and longjmp() OK in c++ code?

Answer 1

If possible I would avoid using setjmp/longjmp, as most C stuff, in C++ code. For what concerns C++ exceptions, as far as I know, they are not deprecated. Indeed, I think it would be very hard to deprecate such a pervasive feature without severely hindering backwards compatibility. It’s possible that you have heard that (some form of) exception specifications, a feature of the recent C++11 standard that was not present in the previous version of the language, has been deprecated during the approval process (see, e.g., this post on Herb Sutter’s blog).

This said, exceptions in C++ are not easy to use well. C++ has lots of features, and sometimes they interplay in very complex ways. Some necessary (but not sufficient) advices are:

• Derive your exceptions from std::exception;
• Manage your resources via RAII;
• Catch by reference, not by value or by pointer.

But the best advice is: understand exactly how exceptions work – precanned advices do not work well. At the purpose, you might read this, this, this and this about how to use exceptions and RAII. Especially “More Effective C++” has a whole chapter dedicated to exceptions, exposing some intricate consequences of apparently simple snippets of code. It raises your overall awareness of the language.