On Thu, Jan 15, 2009 at 4:17 PM, TaeKyeong Wang <bugiii@gmail.com> wrote:
I know BOOST_BINARY. It is a excellent tool, but error message of following expression is confused.
During review there were actually two proposed solutions to representing binary literals -- one was template-based, similar in some ways to your own, and the other was macro based. The macro version is what was accepted for various reasons. While you get an odd error message for BOOST_BINARY( 01234), a mistake which is very clear from looking at the code rather than the error message anyway, you get much better error messages from the macro version for more subtle mistakes such as trying to produce a literal that is too large for an integer to hold (it will give you the same error message your compiler produces for creating an octal literal that is too large). As well, the type of the literal yielded by the macro version follows the exact same rules as those of octal and hex literals in C++, whereas the template version will not. Templates are also notorious for their costly instantiation times and it is generally not worth it to use them for something like this where a pure macro version is available and also more accurately represents the desired behavior. I'm just defending the macro version here, but there are obviously benefits and drawbacks to each approach. If you want to see why the macro version was preferred over the template version, you can always read the reviews. It was by no means a unanimous decision. -- -Matt Calabrese