Re: Desperation with Boost Threads

From:
"Thomas J. Gritzan" <phygon_antispam@gmx.de>
Newsgroups:
comp.lang.c++
Date:
Sat, 24 Jan 2009 00:17:54 +0100
Message-ID:
<gldj7m$1vs$1@newsreader2.netcologne.de>
Johannes Bauer schrieb:

class Thread {
    private:
        boost::thread ThreadID;
    public:
        Thread();
        Thread(const Thread &Other);
        void operator=(const Thread &Other);

        virtual void operator()();
        virtual ~Thread();
};

[...]

Thread::Thread() : ThreadID(*this) {
}

void Thread::operator()() {
    std::cerr << "NOWORK" << std::endl;
}

And an actual implementation:

Thread_Server::Thread_Server() : Thread() {
}

void Thread_Server::operator()() {
    std::cerr << "working" << std::endl;
    while (1) {
        std::cerr << "run" << std::endl;
        sleep(3);
    }
}

This compiles and works. However the derived classes operator() is never
called, only the base classes. This means when I start a thread:

Thread_Server x = Thread_Server();

it only outputs "NOWORK" and terminates. However, as the Thread_Server()
constructor calls the Thread() constructor which creates the actual
boost::thread with *this I assumed that it would make a lookup in the
vtable (virtual operator()!) and start the derived classes working function.


http://www.parashift.com/c++-faq-lite/strange-inheritance.html#faq-23.5

--
Thomas

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