[Threads-devel] Threads and copy constructors...

Subject: [Threads-devel] Threads and copy constructors...
From: oneflewover (thedeerhunter1978_at_[hidden])
Date: 2012-02-18 14:37:54

In the code snippet below, I have one functor that I pass to one 
thread.  As expected, the constructor is called once, but the copy 
constructor is called four times!  As a result, the destructor is 
called five times.

Can someone please explain to me why the copy constructor is called 
four times?  Thanks.

===================================================

class c1
{
    public:

        c1() { }

        c1(const c1& c) { }

        void operator()() { }

        ~c1() { }
};

int main()
{
    c1 c;  // constructor called once here

    //
    // copy constructor called four times here; why?
    //
    boost::thread t1( c1 );

    //
    //  destructor called four times here
    //
    t1.join();

    //
    // destructor called once here
    //
}