--- David Abrahams <[EMAIL PROTECTED]> wrote: > Gennaro Prota <[EMAIL PROTECTED]> writes: > > > On Sun, 08 Dec 2002 12:34:48 -0500, David Abrahams > > <[EMAIL PROTECTED]> wrote: > > > > [snip] > >>> // untested > >>> #define BOOST_PSEUDO_IS_DEFINED(symbol) BOOST_JOIN(symbol, 1) > >>> #define BOOST_WORKAROUND(symbol, test) \ > >>> (BOOST_PSEUDO_IS_DEFINED(symbol) && symbol test) > >> > >>This will fail if "symbol1" is defined, won't it? > > > > Oops, due to the font used when reading mails from Yahoo, I thought > > this was a typo for "symbol" :-s Yes, you are right. It wasn't > > intended as a solution to > > > >>> b) "hides" possible problems in the (unlikely, granted) case that > >>> X is undefined but X1 is and you write: > >>> > >>> BOOST_WORKAROUND(X, test) > >>> > >>> (the result "unexpectedly" depends on the expansion of X1). > > Actually, I tested my solution for that problem and it was OK. That's > the reason I was pasting that long BOOST_NUMERIC_DEFINED_SUFFIX symbol > to it: the idea was that probably nobody defines the > __SUNPRO_CCBOOST_NUMERIC_DEFINED_SUFFIX symbol, for example.
Well, there's no problem with __SUNPRO_CCBOOST_NUMERIC_DEFINED_SUFFIX, just with __SUNPRO_CC1. > Well, then I tested your solution and it was also OK on all the > compilers I have on my machine: > > # include <boost/config.hpp> > > #define BOOST_PSEUDO_IS_DEFINED(symbol) BOOST_JOIN(symbol, 1) > #define BOOST_WORKAROUND(symbol, test) \ > (BOOST_PSEUDO_IS_DEFINED(symbol) && symbol test) > > # define SOME_COMPILER_MACRO1 0 > > # if BOOST_WORKAROUND(SOME_COMPILER_MACRO, > 0) > # error whoops > # endif As I said, when SOME_COMPILER_MACRO1 is defined but SOME_COMPILER_MACRO isn't then the result depends on the expansion of SOME_COMPILER_MACRO1 (and possibly on the test, of course). In this case the condition of the #if becomes: (0 && SOME_COMPILER_MACRO > 0) and then, of course (0 && 0 > 0) Now, try defining #define SOME_COMPILER_MACRO1 5 and change the test e.g. to <= 1200 [...] > BOOST_PP_CAT has several workarounds for broken compilers, and I > wanted to get it right first before worrying about that particular > dependency. Yeah, I noticed that. I don't know what problems do they solve though so I'm not sure if they are needed in the case of BOOST_WORKAROUND. Maybe they have just to do with passing empty arguments? Genny. __________________________________________________ Do you Yahoo!? Yahoo! Mail Plus - Powerful. Affordable. Sign up now. http://mailplus.yahoo.com _______________________________________________ Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost
