How do I clear the std::queue efficiently?

Question

I am using std::queue for implementing JobQueue class. ( Basically this class process each job in FIFO manner). In one scenario, I want to clear the queue in one shot( delet

Answer 1

Another option is to use a simple hack to get the underlying container std::queue::c and call clear on it. This member must be present in std::queue as per the standard, but is unfortunately protected. The hack here was taken from this answer.

#include 

template
typename ADAPTER::container_type& get_container(ADAPTER& a)
{
    struct hack : ADAPTER
    {
        static typename ADAPTER::container_type& get(ADAPTER& a)
        {
            return a .* &hack::c;
        }
    };
    return hack::get(a);
}

template
void clear(std::queue& q)
{
    get_container(q).clear();
}

#include 
int main()
{
    std::queue q;
    q.push(3);
    q.push(5);
    std::cout << q.size() << '\n';
    clear(q);
    std::cout << q.size() << '\n';
}