How do I add a custom filter in log4cplus?

Question

This is a followup to this question on conditional logging.

I found examples in the log4cplus test directory of how to configure filters in the properties file (so

Answer 1

The error was a result of mislocating the libraries built from log4cplus.

So, the example above is the way to implement a custom filter in log4cplus. Unless anyone objects I will leave this here as there are very few examples of log4cplus filters on the web.