C++ Truths

Compile-time algorithm selection can be done using function overloading and traits idiom . It is a quite useful technique in generic programming. In this technique usually a set of "selector" types are used to select one among many overloaded functions. Note that the number of parameters to these overloaded functions is same but there is a "selector" type at the end of the parameter list. A use of that technique based on standard defined iterator tags is shown here .

std::bad_exception is a useful device to handle unexpected exceptions in a C++ program , which works in conjunction with unexpected_handler. unexpected_handler and terminate_handler are a traditional way of dealing with unknown exceptions. std::set_unexpected () and std::set_terminate () functions let us register custom handlers instead of standard handlers, which usually abort the program. More information can be found here . Assuming g++ 4.0.2 complies with the standard in this area, I verified that if function f() throws an exception that is not listed in its exception specification list, our custom function pointed to by the unexpected_handler is invoked if we have set one. If our custom handler rethrows whatever unknown exception caused the unexpected() to be invoked, following things happen. * If the exception specification of f() included the class std::bad_exception , unexpected() will throw an object of type std::bad_exception, and the C++ run time will search for another