How to release pointer from boost::shared_ptr?

Question

Can boost::shared_ptr release the stored pointer without deleting it?

I can see no release function exists in the documentation, also in the FAQ is explained why it

Answer 1

Kids, don't do this at home:

// set smarty to point to nothing
// returns old(smarty.get())
// caller is responsible for the returned pointer (careful)
template 
T* release (shared_ptr& smarty) {
    // sanity check:
    assert (smarty.unique());
    // only one owner (please don't play games with weak_ptr in another thread)
    // would want to check the total count (shared+weak) here

    // save the pointer:
    T *raw = &*smarty;
    // at this point smarty owns raw, can't return it

    try {
        // an exception here would be quite unpleasant

        // now smash smarty:
        new (&smarty) shared_ptr ();
        // REALLY: don't do it!
        // the behaviour is not defined!
        // in practice: at least a memory leak!
    } catch (...) {
        // there is no shared_ptr in smarty zombie now
        // can't fix it at this point:
        // the only fix would be to retry, and it would probably throw again
        // sorry, can't do anything
        abort ();
    }
    // smarty is a fresh shared_ptr that doesn't own raw

    // at this point, nobody owns raw, can return it
    return raw;
}

Now, is there a way to check if total count of owners for the ref count is > 1?