I'm always banging on to clients about the importance of periodically running code cleanup scripts over their code bases. One of the ones I recommended is a trailing spaces remover, essential for C/C++ code because of the dangerous effects it has on macros, and the concomitant difficulty of finding the problem(s). And yesterday I got caught by just such a situation, having failed to follow my own advice.

I'm in the process of adding some final touches to Pantheios before its (highly overdue) final 1.0 non-beta release. One of these is adding some examples illustrating how log statements may be targeted at certain back-ends by using the facilities for "overloading" the severity levels, i.e. combining a bona-fide severity level with additional information that may be used by a multiplexing/composite back-end to route the statement to specific concrete back-end(s). The details of what this all mean are somewhat outside this discussion, so suffice to say that it's the difference between, say

  #include <pantheios/pan.hpp> // gives us the 'pan' namespace alias, for brevity

  std::string general("general");

  pantheios::log(pan::notice, "A statement of ", general, " importance");

  #include <pantheios/pan.hpp> // gives us the 'pan' namespace alias, for brevity

  int beidSpecial = . . . // The identifier of the specific back-end to which the statement will be targetted

  std::string specific("specific");

  pantheios::log(pan::notice(beidSpecial), "A statement of ", specific, " importance");

These facilities have been available for the library for a very long-time, at least a year or so. But in writing the tutorial it became clear to me that users who're employing Pantheios in their C programs are somewhat left out in this regard. So I added the PANTHEIOS_MAKE_EXTENDED_SEVERITY() macro"

#define PANTHEIOS_MAKE_EXTENDED_SEVERITY(sev, xi28)   \
                                                      \
    (((sev) & 0x0f) | (((xi28) << 4) & ~0x0f))

H:\freelibs\pantheios\current\include\pantheios/pantheios.h(557) : error C2143: syntax error : missing ')' before '&'
H:\freelibs\pantheios\current\include\pantheios/pantheios.h(557) : error C2059: syntax error : ')'

I'm embarassed to admit that I had to sleep on this one before I had the mental wherewithall to realise my mistake, and to cause the IDE to show spaces. In that case the macro definition actually looks like the following (with the symbol « used to represent a space):

#define«PANTHEIOS_MAKE_EXTENDED_SEVERITY(sev,«xi28)«««\«««
««««««««««««««««««««««««««««««««««««««««««««««««««««««\
««««(((sev)«&«0x0f)«|«(((xi28)«<<«4)«&«~0x0f))

So, take the advice, as I will myself try to do more thoroughly, and strip those trailing spaces. I use a simple Perl script which is executed either by find (on UNIX) or for on Windows.

I'd love to hear from anyone who's had similar experiences, especially where they involve a little humbling stupidity. ;-)