Nick made a comment about code folding, and I promised him an essay. Here it is. It’s not very long.
I like code folding. When I know a mature project well, and the modules are kinda big, I want to open a file and not be distracted by seeing things I’m not working on.
I dislike code folding. When I don’t know a project well, I want to be able to see everything without having to drill down into it. When I do know it well, I want the modules to be small enough that there’s just one topic in each file, and so opening a file does the thing that opening a code fold is supposed to do.
So, the second case is ideal, but also idealistic—and we don’t live in an ideal world. Sometimes there are other pressures against breaking a project into a billionty well-named modules, too, and you have to live with the fact that a given module might have some variety of content.
Code folding, like window focus, should ideally follow my unknown innermost desires—the computer should always know just what I want without my having to tell it. Alas.