With the new option, the library can be compiled with the entire
logging infrastructure disabled. The public api remains unchanged, but
the internal logging functions will have no effect anymore.
In practice the overhead of the logging functions should be quite
small, and disabling the logging at runtime might be more convenient.
Especially because troubleshooting will become much harder without any
logging.
The new convenience function provides a centralized and threadsafe
function for logging system errors. The previous functions are
deprecated and will be removed after the transition to the new context
based logging.
An application can now register an application defined callback
function, which will perform the actual logging. This provides
additional flexibility compared to logging to stderr with a hardcoded
format. Applications can now easily display the messages in their user
interface, customize the format, etc.
Although the internal logging function is a printf like function, the
arguments are converted into a plain string before being passed to the
callback function. This greatly improves interoperability with
programming languages which don't support C style variadic functions
(e.g. Python, C#, etc).
With the introduction of a context object, library initialization and
shutdown can be performed without requiring any global state. A single
process can use multiple independent contexts without any problems. The
lack of a global state also improves the thread-safety of the library.
At the moment, the new context object is primary used to implement an
improved logging system.
