How can I launch a member function as a std::async task, which returns a std::tuple.
Sample code:
#include <iostream>
#include <future>
#include <tuple>
#include <numeric>
class Foo {
bool calc;
public:
Foo(bool b) : calc(b)
{}
std::tuple<long, double> calc(std::vector<int> a) {
long sum = 0;
double avg = 0.0;
if ((*this).calc) {
long sum = std::accumulate(a.begin(), a.end(), 0);
double avg = sum / a.size();
}
return std::make_tuple(sum, avg);
}
void call_calc(std::vector<int> i) {
auto handle = std::async(&Foo::calc, this, i);
auto resultTuple = handle.get();
std::cout << "Sum = " << std::get<0>(resultTuple) << " Average = " << std::get<1>(resultTuple) << std::endl;
}
};
int main() {
std::vector<int> a{ 2, 5, 6, 7, 3 };
Foo foo(true);
foo.call_calc(a);
}
In this example, without the member variable, code works fine. The above code is throwing compilation error for following lines:
auto handle = std::async(&Foo::calc, this, i);
Error: No instance of overloaded function 'std::async' matches the argument list.
std::cout << "Sum = " << std::get<0>(resultTuple) << " Average = " << std::get<1>(resultTuple) << std::endl;
Error: No instance of overloaded function 'std::get' matches the argument list.
