Call a function before function exits

Question

I will begin with an example. Suppose I need to guard a code with a function inside a mutex. There are two ways of implementing this.

#include 
#         


        

Answer 1

You may write your own geneirc RAII class, something like:

class Finally
{
public:
    explicit Finally(std::function f) : mF(f) {}
    ~Finally() noexcept() {
        try
        {
            mF();
        } catch (...) {
            // Handle error.
        } 
    }

    Finally(const Finally&) = delete;
    Finally(Finally&&) = delete;

    Finally& operator=(const Finally&) = delete;
    Finally& operator=(Finally&&) = delete;

private:
    std::function mF;
};

Usage:

{
    pthread_mutex_lock(&myMutex);
    Finally finally([&](){ pthread_mutex_unlock(&myMutex); });

    //..
}

Even if a dedicated RAII object may be more appropriate in some case (as Mutex).