C++ Catching exceptions in constructors

When deciding whether to catch the exception, especially one thrown during construction, ask yourself a very simple question, if you do catch it can you still leave the class in a usable state? If the answer is yes, then by all means catch it, deal with it and allow construction to continue. If the answer is no then do not catch it! Why? Simple! if you catch and swallow it, how is the code that was attempting to construct your class to know that the class is unusable (or, at least only partially constructed)? Continue reading

C++ Throwing exceptions from destructors

You’re implementing a beautiful class. It’s just wonderful – the most perfect code you’ve ever written, except… for some reason it keeps crashing and you don’t know why. You’ve debugged the code and discovered it happens when your class goes out of scope and needs to throw an exception from the destructor. Tested in isolation, this works fine but integrated into the main code base it causes a crash. You know there are exception handlers that should deal with this and yet it still crashes. This doesn’t make sense. Why is the crashing? Continue reading

C++ Passing by value vs. passing by reference

In C++ all arguments are passed to functions by value. In other words, a copy of the value is taken and that is what the function has to work with. If you want to modify the original value you must either pass a pointer or reference to the original value you wish to modify. Of course, even the pointer or reference are still passed by value. Pointers and references are just another C++ type and when they are passed around you do so by value. Continue reading