> copy_if on a multidimensional container should not naively copy entire > hyperplanes. More generally, I think that whenever an arbitrarily large > object is to be copied, that should be explicit instead of implicit. A > lot of focus in C++ is dedicated to making sure you don't copy the wrong > thing.
In my opinion by-value-types are good for mathematical objects and data like numbers, tuples, sets, lists, vectors, dictionaries etc., by-reference-types are good for things like graphical objects/widgets, hardware-ressources, io- handles, factories etc. Unnecessary copies? The compiler should care about that, I want to have clear semantics and generic syntax.
