Method invocable_wrapper

cpp/include/proton/work_queue.hpp:65–65

struct invocable_wrapper {
    invocable_wrapper(): wrapped_(0) {}
    invocable_wrapper(const invocable_wrapper& w): wrapped_(&w.wrapped_->clone()) {}
    invocable_wrapper& operator=(const invocable_wrapper& that) {
        invocable_wrapper newthis(that);