John's library has a concept called destination which sounds like your sink. There is another concept called formatter which, well, formats
oh yes, i call that filters, but are merely appenders.
In my opinion one of the most important questions is what else can a Boost logging library offer than what we can do today with:
clog << "Logging ...";
As we can easily redirect clog or replace it with another stream object where we can control the buffer there must be some added value?
oh, you almost got me there.. i did not considered these << operators when designing. mainly because of their annoying syntax. i am simple man i prefer that one of printf :) (or boost::format) so i took approach more in the style of type-safer printf using variadic templates combined with classic macro-witchery. i have to take a very close look on John's library to find out where lies the differences in interface. perhaps there won't be any. definitely my planned added value is run-time efficiency (with focus multithreaded environment). many thanks for you attention, Mojmir