How to use std::async on a member function?
Something like this:
auto f = std::async(&Person::sum, &p, xxx);or
auto f = std::async(std::launch::async, &Person::sum, &p, xxx);where p is a Person instance and xxx is an int.
This simple demo works with GCC 4.6.3:
#include <future>#include <iostream>struct Foo{ Foo() : data(0) {} void sum(int i) { data +=i;} int data;};int main(){ Foo foo; auto f = std::async(&Foo::sum, &foo, 42); f.get(); std::cout << foo.data << "\n";}
There are several ways, but I find it's most clear to use a lambda, like this:
int i=42;Person p;auto theasync=std::async([&p,i]{ return p.sum(i);});This creates a std::future. For a complete example of this, I have a full example including a async-capable setup of mingw here:
http://scrupulousabstractions.tumblr.com/post/36441490955/eclipse-mingw-builds
You need to make sure that p is thread safe and that the &p reference is valid until the async is joined. (You can also hold p with a shared pointer, or in c++14, a unique_ptr or even move p into the lambda.)