On 06/27/2011 10:37 PM, Edward Diener wrote:
May I suggest the addition of a macro that strips parentheses but only if they are present?
I do not think this is possible. But I am out of the loop regarding pp-lib additions and Paul would really know if this could be done.
Code to do this was already given on the Boost ML by Steven Watanabe: <http://article.gmane.org/gmane.comp.lib.boost.user/61011> I've already been using this for a year in my code, and it works fine. There is one little caveat with the above code, it's not strictly conforming to C99/C++0x so it doesn't work with Wave. Replacing (__VA_ARGS__, 2, 1) by (__VA_ARGS__, 2, 1, 0) fixes the problem.
I have found this to be very useful for passing arguments that contain commas easily.
Can you give an example of what you are trying to do ?
Consider something like BOOST_FOREACH(std::pair<A, B> a, mymap) this fails because the preprocessor sees it as three arguments. Assuming BOOST_FOREACH was using STRIP_PARENS on its arguments, you could do BOOST_FOREACH((std::pair<A, B> a), mymap) in the cases where it is necessary. This is actually pretty much a requirement when you want to write macros that take template with multiple parameters as arguments.