On Sunday 01 September 2013 03:27:06 Daryle Walker wrote:
Date: Wed, 28 Aug 2013 12:14:51 +0400 From: andrey.semashev@gmail.com
1. BOOST_EXPLICIT_OPERATOR_BOOL() macro for defining explicit operator bool() for a class.
I could add this to my touch-ups of Boost.Rational, but I see two minor problems using it:
a. It isn't marked "constexpr." I can add that myself before using "BOOST_EXPLICIT_OPERATOR_BOOL" in "boost/rational.hpp," but what happens if someone corrects it in "explicit_operator_bool.hpp"? Will the (temporary) double definition cause an error?
Well, since there isn't a constexpr_if or something, I don't see a way to add it to BOOST_EXPLICIT_OPERATOR_BOOL. I could add BOOST_EXPLICIT_OPERATOR_BOOL_PP(pre, post), which would add pre() and post() before and after the operator signature. For example: BOOST_EXPLICIT_OPERATOR_BOOL_PP(\ BOOST_PP_IDENTITY(BOOST_CONSTEXPR), BOOST_PP_EMPTY()) would expand to something like constexpr explicit operator bool() /* nothing */ { ... } Although I'm not sure the expansion will be correct if BOOST_CONSTEXPR expands to nothing. PP gurus? A simpler alternative would be just BOOST_CONSTEXPR_EXPLICIT_OPERATOR_BOOL macro.
b. Its #included Boost.Log-specific configuration header file flags an error if RTTI isn't active. And it's unconditional, which would make Boost.Rational unusable for small environments that skip RTTI. But I don't know if Boost.Rational is already unsuitable for such systems, since it uses exceptions and such.
It won't include these headers after extraction and it won't require RTTI.