On 8/5/05, John Torjo <john.lists@torjo.com> wrote: <snip>
2. Is it possible to query for the current logging level? If logging activities take a significant amount of time, but they won't be output, you don't want to do them. As an example - I've written
For Boost.Log, if a message should not be outputted, logging activities won't take place.
It's something like this: // pseudocode if ( !should_write_msg(log,some_level) ; else log.stream()
So when you write:
BOOST_LOGL(lg,err) << "this " << "is an error" << std::endl;
is equivalent to:
if ( !should_write_msg(lg,err)) ; else lg.stream() << "this " << "is an error" << std::endl;
libraries to decode debug information (Dwarf, Stabs etc). These would at a high logging level, construct and output a textual equivalent of a debug record (which took significant time). The text construction wouldn't be done unless log output was going to be done.
Is this what you wanted?
Best, John
John - you should have told me to RTFM! I've found exactly what I wanted on the 'Efficiency' page. This is the sort of thing I want to do: if (<some-log>()(boost::logging::level::my_error)) { std::ostringstream oss; // v is a vector<int> std::copy(v.begin(), v.end(), std::ostream_iterator<int>(oss, ", ")); BOOST_LOGL(<some-log>, my_error) << oss.str() << "\n"; } Now, that example can be modified to write to the logging stream directly using this: std::copy(v.begin(), v.end(), std::ostream_iterator<int>(*<some-log>().stream().stream(), ", ")); BOOST_LOGL(<some-log>, my_error) << "\n"; First question - is this usage that you envisaged? . Secondly, the output is 09:30:35 [app] 0, 1, 2, 3, 09:30:35 [app] rather than 09:30:35 [app] 0, 1, 2, 3, because of the second log statement prepending the time before the "\n". Is there any way of getting the required output using the above code pattern, by somehow stopping the log modifiers? Stuart Dootson