Hi.
I checked out the optional library and found it to be of great value. I
have, however, a few small suggested improvements (and no, I'm not
talking about the pointer/container/discriminated-union semantics
debate; I read this discussion in the mail archives and I also saw the
resulted library and I'm very happy with what came of it).
I'm talking about the detail::none_t part.
Should it really be in the detail namespace? Isn't that a little weird?
The detail namespace should be "forbidden area" for the users, yet here
they are offered to write code like
my_optional = boost::detail::none_t();
One might argue that there's the 'none' global variable which will make
the code look like
my_optional = boost::none;
which looks much better. I agree that it looks much better, but it still
doesn't make the previous way of thinking (crating a temporary none_t
instance) illegal or unsupported. It is unsupported now.
And while we're at the global none variable, I have to say that the
reason I first tried the temporary-none_t-instance way, is that I didn't
know of 'none'. The documentation is very poor on this subject. It's
only mentioned in one place in a short, unexplained sentence, and it's
in the "Detailed Semantics" section which no one ever bothers to read
anyway.
In addition to improving the docs, I'd say that it's even better to
include the boost/none.hpp header with optional.hpp so it could be
easily found and reached. As I understood, the reason why this is not
done now, is because some compilers (such as Borland's) have troubles
with initialized data and pre-compiled headers. If this is truely the
case, then I think it's easily solved. Include as follows:
#ifndef BOOST_OPTIONAL_DISCLUDE_NONE
#include