Pass parameters to std::thread wrapper

Question

I want to implement a small thread wrapper that provides the information if a thread is still active, or if the thread has finished its work. For this I need to pass the functio

Answer 1

O'Neil and DeiDei got here first, and they're correct as far as I can tell. However, I'm still posting my solution to your problem.

Here's something that would work better:

#include 
#include 
#include 

class ManagedThread {

public: /* Methods: */

    template 
    explicit ManagedThread(F && f, Args && ... args)
        : m_thread(
            [func=std::forward(f), flag=&m_active](Args && ... args)
                    noexcept(noexcept(f(std::forward(args)...)))
            {
                func(std::forward(args)...);
                flag->store(false, std::memory_order_release);
            },
            std::forward(args)...)
    {}

    bool isActive() const noexcept
    { return m_active.load(std::memory_order_acquire); }

private: /* Fields: */

    std::atomic m_active{true};
    std::thread m_thread;

};

It makes use of lambdas instead, and correctly uses std::atomic instead of volatile to synchronize the state, and also includes the appropriate noexcept() specifiers.

Also note, that the underlying std::thread is not joined or detached properly before destruction, hence leading to std::terminate() being called.

I rewrote the test code as well:

#include 
#include 

int main() {
    ManagedThread mt1(
        []() noexcept
        { std::this_thread::sleep_for(std::chrono::milliseconds(500)); });
    std::cout << "thread 1 active = " << std::boolalpha << mt1.isActive()
              << std::endl;
    std::this_thread::sleep_for(std::chrono::seconds(1));
    std::cout << "thread 1 active = " << std::boolalpha << mt1.isActive()
              << std::endl;
}