try catch finally construct - is it in C++11? [duplicate]

Answer 1

Not an excuse to forgo RAII, but useful when e.g. using non RAII aware APIs:

template<typename Functor>
struct finally_guard {
    finally_guard(Functor f)
        : functor(std::move(f))
        , active(true)
    {}

    finally_guard(finally_guard&& other)
        : functor(std::move(other.functor))
        , active(other.active)
    { other.active = false; }

    finally_guard& operator=(finally_guard&&) = delete;

    ~finally_guard()
    {
        if(active)
            functor();
    }

    Functor functor;
    bool active;
};

template<typename F>
finally_guard<typename std::decay<F>::type>
finally(F&& f)
{
    return { std::forward<F>(f) };
}

Usage:

auto resource = /* acquire */;
auto guard = finally([&resource] { /* cleanup */ });
// using just
// finally([&resource] { /* cleanup */ });
// is wrong, as usual

Note how you don't need a try block if you don't need to translate or otherwise handle exceptions.

While my example makes use of C++11 features, the same generic functionality was available with C++03 (no lambdas though).

Answer 2

You don't need finally in C++ because C++ has RAII which is much nicer.

Answer 3

C++11 does not add support for finally. The decision makers (especially Stroustrup) have for many many years expressed a preference for other idioms, i.e. RAII. I think it is exceptionally unlikely that C++ will ever include finally.