On Monday 11 March 2013 02:24:44 Darren Garvey wrote:
Hi Andrey,
I'm glad you've added the trivial logger. As big as that warning is in the documentation, it would be more reassuring to see that this logger supports lazy evaluation of the logging expression if the example demonstrated it. eg.
// Note: some_very_expensive_operation() won't be called unless debug logging is enabled. BOOST_LOG_TRIVIAL(debug) << "A debug severity message" << some_very_expensive_operation();
Regardless of the logger you use, that's the case; the streaming expression won't be evaluated if the filter does not pass the record. It's mentioned in the docs in several places.
I don't see a way to compile out certain levels of log messages using compile-time flags with the syntax Boost.Log uses. Many other logging libraries choose to put the logging expression as part of the macro, which makes it easy to support this usage pattern. Have you considered supporting this?
Yes, the idea floated around since the early days of the library. However, it doesn't seem feasible without restricting to particular severity levels, so I didn't implement that. You can always define your severity levels and your logging macros that will use them and selectively expand these macros to nothing depending on the configuration.