error: passing ‘const TemporaryQueueWriter’ as ‘this’ argument discards qualifiers [-fpermissive]
   82 |  while (obj.state())

struct A {
void foo() const {}
};

class TemporaryQueueWriter: public BasicThread {
public:
    void SetTestimonySource(std::function<void(TemporaryQueueWriter &)> testimony_queue_writer){
       _testimony_queue_writer = testimony_queue_writer;
    }
    void StartThread();
    void Stop(); 
    bool state(){
        return running;
    }
    void change_state(bool r){
        running = r;
    }

protected:
    void Run() override;
    void OnWaitForStop() override;
private:
    std::atomic<bool> running;
    std::function<void(TemporaryQueueWriter &)> _testimony_queue_writer;
};

void TemporaryQueueWriter::Run() {
    _testimony_queue_writer();
}

error: no match for call to ‘(std::function<void(TemporaryQueueWriter&)>) ()’