Vladimir is right. You've seen the problems and crashes that leaving type checking to the programmer causes. You need the compiler to do the checking for you. I suggest using the same kind of scheme as the iostreams library. You might want to do more design than this - but you could start by adding a small family of global functions that look like... (you'll have to work up any varargs support stuff - I don't remember it) MyLogger & operator << (MyLogger & logger, int i) { logger.dump("%d", i) ; } MyLogger & operator << (MyLogger & logger, char * str) { logger.dump("%s", str) ; } This will allow you to write... MyLogger Log .... Int I ; Log << 10 << "abc" << I ; ...it will be (mostly) type safe - the type dangerous stuff is isolated to one place per output type - and you can extend it as you go. You'll likely need extra formatting stuff and that's where boost::format may help you. HTH - Richard -----Original Message----- From: boost-users-bounces@lists.boost.org [mailto:boost-users-bounces@lists.boost.org] On Behalf Of Vladimir Prus Sent: 22 December 2004 10:45 To: boost-users@lists.boost.org Subject: [Boost-users] Re: Q: boost::format : can formatting variablearguments lists be done ? Dan Dimerman wrote:
Currently I have a piece of code that logs messages much in the same way as printf() :
void MyLogger::dump( const std::string& format, va_list& list ) { const unsigned short buf_size = 1024; char buffer[ buf_size ]; ::memset( buffer, 0, buf_size ); ::_vsnprintf( buffer, buf_size - 1, format.c_str(), list);
/.../ }
After many headaches (and crashes) due to mistaken format specification fields, I thought to upgrade my class's API to use boost::format, but alas, I couldn't find the way to feed the format object from a va_list. Is there a way?
Why do you think that boost::format together with va_list will be any safer than vsnprintf? If boost::format accepted va_list, it would have to guess types from format string, which will be as dangerous as it is for vsnprintf. - Volodya _______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users -- No virus found in this incoming message. Checked by AVG Anti-Virus. Version: 7.0.296 / Virus Database: 265.6.3 - Release Date: 21/12/2004 -- No virus found in this outgoing message. Checked by AVG Anti-Virus. Version: 7.0.296 / Virus Database: 265.6.3 - Release Date: 21/12/2004