Launch asyc a method from a class in C++

Question

I am using C++14 and would like to launch a method from a class instance which is stored in unique_ptr. A very simple version of my code looks like:

class foo {
  void run_server() {
    // Do some stuff.
  }
};

auto ptr = make_unique<foo>();
auto res = std::async(std::launch::async, ptr->run_server());

I get compile error when I compile my code and the error message says that there is no match to call async. I think there is a way to launch methods of an instantiated class using lambda function but I am not sure how or whether this is a solution in my case. Any help is appreciated. Thanks.

Answer 1

You can use a lambda to achieve this BUT passing a unique_ptr to a lambda means you move it to lambda and then it is destroyed when the lambda returns.

You could try this:

class foo {
public:
    void run_server() {
        // Do some stuff.
    }
};

int somefunc() {
    auto ptr = std::make_unique<foo>();
    auto p = ptr.get();

    auto theasync=std::async( std::launch::async, [p]{ p->run_server() ;});
    //do whatever...
    return 0;
}