Thinking of possible approaches to class library interface design I reread the post by Martin Fowler titled Fluent Interface. Although I never tried out this approach in designing my own class libraries it looks like with modern IDE such interfaces will really be "fluent" with use of code completion. Now I'm trying to arrange some time to deeper research this topic. So far I've seen that such interfaces work great for Builder-like methods and stream-like operations. Would be interesting to see how good they are in regular development practice.