At 23:03 18/03/2004, you wrote:
Rob Stewart wrote:
From: "Neal D. Becker" <ndbecker2@verizon.net>
John Torjo wrote:
Neal D. Becker wrote:
I notice boost doesn't have a logging library. I have seen several floating around. Are there any recommendations?
How about std::ostream ;) ?
Also, disabling writing to a stream is fairly easy, by setting the failbit of a stream object: out.setstate( std::ios::failbit); // nothing gets written to this log any more
Interesting idea. I would like the overhead of disabled loggers to be relatively small. Would you think this technique might be useful in that case? (Of course, relatively small is a relative term).
Every insertion and every mf you call on the stream must occur and must check the failbit flag. It would, therefore, have noticeable overhead. Is it a problem? Maybe. You could time an app with the logging compiled away (via preprocessor) and with the failbit set.
I think it's the wrong approach. In our company we have implemented logging through macros which has one very important property: When I write
LOG_DEBUG( whatever() );
into my source, then whatever() is only evaluated when the debug-logger is active. The macro basically expands to something like this:
if( Base::hasLogger( LogLevel::DEBUG ) ) Base::log( whatever(), LogLevel::DEBUG );
I think this cannot be done without macros as normal function calls (including operator<< for streams) need to evaluate their arguments before they are called. As the difference in the application execution speed can vary by a factor of 1000, this is a very valuable optimization for us. My 2ยข.
Personally I think restricting boost to disabling logging on a #define is a double negative... ie a no no. It would be fine if boost was just used in developing "packaged" software, but in the real world where customers buy a big product *and* support, its very useful to be able to turn debugging on/off at runtime with the delivered solution. Having said that the previous post I think that's on the right lines, tho in the code we use don't hide behind a macro, for example my preferred syntax if (debug_trace.enabled()) { report(debug_trace, .... ) << "Somethings gone wrong x=" << x; } Very simple to use... you just have to instill into the team that reports stream operators cost, and you better check if the trace is enabled :o) I guess you could get the best of both worlds and wrap it up in a macro #define BOOST_LOG(Trace, ...., Message) \ if (Trace.enabled()) { report(Trace, .... ) << Message; } which is kind of getting to something similar to the previous post. Regards Mark --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.614 / Virus Database: 393 - Release Date: 05/03/2004