intrusive_ptr detach method

[nn-mail@…]

It is very handy. In some cases like passing between threads or between functions.

(e.g. Boost.ASIO needs this too)

Instead of writing this code:

intrusive_ptr<A> a(get_a());

intrusive_add_ref(a.get());
call(a.get());

One could write

intrusive_ptr<A> a(get_a());

call(a.detach());

The good thing in the second variation that we don't increase counter, so no 'lock' opcode to the processor. Better performance.

Patch:

        void* detach()
        {
                T * tmp = px;
                px = 0;
                return tmp;
        }

Thanx.

[avi@…]

Improved patch (test + docs)

[Peter Dimov]

Applied in ​https://github.com/boostorg/smart_ptr/commit/73153d57971849d6cfd13e2bd1bf2b0c9894797d

[NN]

Actually 'release' name is much better, cause we have unique_ptr::release. Didn't think about it.. What do you think about changing the name ?

[Peter Dimov]

We decided that detach is a better name than release, both because unique_ptr::release gives you a pointer that you own exclusively, and because of the potential confusion between intrusive_ptr::release and intrusive_ptr_release.