Question

I’m using boost 1.51 on multiple platforms and compilers without C++11.

In my main thread I have a very long, expensive to copy, std::string veryLongString, that I need to pass to a new thread for processing.
After the new thread is created I have no more use for veryLongString on the main thread so I’d like to move it into the boost::thread ctor.
The main thread, or the scope of veryLongString may end before the new thread completes, so passing by reference (e.g. with boost::ref) is not an option.

Obviously, if veryLongString was created as a shared_ptr<std::string> then I could just copy the shared_ptr into the thread ctor, but it wasn’t, so I’d need to copy it anyway.

How can I [boost::]move() veryLongString into the boost::thread ctor (probably using via boost::bind)?
Is this possible?

Answer 1

If the string is expensive to copy, pass something holding it but less expensive to copy. For example, you can use a shared_ptr<std::string>. You can pass the shared pointer to a suitable wrapper which calls the function you actually want to get called (and probably taking the argument by reference or const reference).

To get the string into a shared pointer you might need to move it there:

shared_ptr<std::string> ptr(new std::string);
ptr->swap(your_long_string);