Christopher Kohlhoff wrote:
Hi Peter,
--- Peter Dimov <pdimov@mmltd.net> wrote:
Why is
http://asio.sourceforge.net/boost-asio-proposal-0.3.6/libs/asio/doc/tutorial...
using raw pointers, strdup, new, free and delete? This is soo 1996. Tutorials shoud teach.
Yep, this already came up in a review and I'm planning to change it. IIRC, the motivation for doing it this way was:
- to avoid introducing too many boost facilities at once
- to illustrate the "exactly-once" callback invocation
Since I want to keep the tutorial as simple as possible, I'm a bit undecided about what to put instead though. I want to ensure that whatever I use instead doesn't distract from the things that I am trying to teach.
But the C-style facilities used in the tutorial actually do serve as a distraction to me, not just a mere annoyance. I am now forced to think of the following: - what happens if something along the way throws? - does the author of the tutorial really endorse this programming style, and do I want to use a library designed with this use style in mind? - if the tutorial doesn't show the recommended way to use asio, what _is_ the recommended way to use it?
For example, one option I'm considering is to simply replace them with shared_ptr<socket>, shared_ptr<std::string> etc, but keep using free functions as callbacks. The "distraction" I see with std::string is that I probably need to explain how calling asio::buffer() on it uses the data() member function, and the conditions under which the pointer returned by data() is invalidated.
shared_ptr<socket> is the easy part, although this immediately leads me to ask the obvious question: why isn't a socket already a shared_ptr<socket_impl>? For the string, my first thought was to just pass a std::string by value. This of course doesn't work because the string needs to stay alive until the operation is complete, so we need something like a shared_array<char>. I think that the library should provide one. In summary, I think that eliminating the C-style facilities from the tutorial will improve both the tutorial and the library.