That all makes sense, I agree totally. One of the challenges with this sort of unmotivated code (unmotivated in a literal sense, not a derogatory sense -- we d

That all makes sense, I agree totally. One of the challenges with this sort of unmotivated code (unmotivated in a literal sense, not a derogatory sense -- we don't know what's motivating it) is that it's very hard to know how general a solution to design. I love the C++ template universe when things "just work," but it's very easy to get into a cycle where just a /bit/ more complexity gets you a /bit/ more generality -- only to realize that after beautifully polishing that modular code, you only use it in one or two contexts. std::apply is a good example of putting that generality and complexity into the standard library; if a caller can then use that directly, even with loss of generality, that's usually my preference. If nothing else, it means folks encountering the caller will have fewer layers to understand, and many fewer non-standard layers.