On Sat, 05 Jul 2008 17:43:04 +0200, Sebastian Redl <sebastian.redl@getdesigned.at> wrote:
Boris wrote:
Thanks for the link! I'm currently comparing the code and have already a question: There was a static constant defined in one class which has been changed by Julio to a static method (it had caused problems when the header was included in more than one compilation unit). Julio couldn't use the macro BOOST_STATIC_CONSTANT (see http://www.boost.org/development/int_const_guidelines.html) as on Windows a complex type is used which must be defined outside the class. While Julio simply defined a static method I had fixed the code with:
#if defined(BOOST_POSIX_API) || defined(BOOST_PROCESS_DOXYGEN) BOOST_STATIC_CONSTANT(handle_type, INVALID_VALUE = -1); #elif defined(BOOST_WINDOWS_API) # define INVALID_VALUE INVALID_HANDLE_VALUE #endif
Is there any guideline what to prefer here?
Macros as constants are pretty much shunned. Worse, the two options here have different behaviour if they're not on the global namespace. (And also if they are, since the macro prevents all other uses of the name.)
I should have written the code differently: #if defined(_MSC_VER) # define INVALID_VALUE INVALID_HANDLE_VALUE #else BOOST_STATIC_CONSTANT(handle_type, INVALID_VALUE = -1); #endif Now it's obvious that the macro is a workaround for VC++ only. While Sebastian's points are valid do they justify to change a class' interface because of a limitation of one compiler? I've no preference (especially as VC++ is not an unimportant compiler of course). Boris