On 9/13/07, Howard Hinnant <hinnant@twcny.rr.com> wrote:
I am requesting comments, both for and against a "sticky exception". [...] Do you see a use for such a class? Would you use it? Would you want libraries you're using to use it? Do you have real world example conditions which fit this use case? Or is it just evil (and why)?
I think it might be a little too much on the evil side. Wouldn't it break otherwise exception safe (if admittedly not very elegant) code like the following? template<typename F> bool foo(F f) { bar = acquire-resource-bar() bool failed = false; try { f(); } catch (....) { failed = true; } release-resource-bar(bar); return failed; } Foo would work correctly for any function-like objects, except for those that throw sticky exception. void baz() { sticky_exception s throw s; } int main() { foo(baz); // XXX leaks a bar!! } That is, you can't throw a sticky exception unless everything in the call stack is capable of handling it, else you might leak. I know that the preferred idiom for exception safety is RAII (Which is also sticky-exception-safe), but sometimes it is cumbersome to write a RAII wrapper just for one use. HTH, gpd