On Wednesday, 29 March 2017 at 09:50:10 UTC, abad wrote: > > Is this on purpose and what's the rationale? In Andrei's book, chapter 6.9.1 "the non virtual interface (NVI) idiom" answers your question. It cites this article by Herb Sutter as the originator of the idea: http://www.gotw.ca/publications/mill18.htm