Earlier quoted context omitted.
This feels like a good area for tooling (editors, source hosts, SCM extensions) to improve experience. I don’t always mind large source files (and sometimes may prefer them over large file system hierarchies), but the can be a pain to navigate in some circumstances. As an example, making several related changes in very different parts of a file, where you need to cross-reference between them. The changes themselves m…
This is how older editors like emacs work. You interact with views/windows/tabs called buffers and those buffers can have files loaded into them. Multiple buffers can reference the same code file but view different sections simultaneously. So you can investigate or edit different parts of one huge file the same way you would smaller ones.
I use JOE and JOE also supports multiple views into the same file. In fact, to open another file is two commands: the open view/window (^KO) command followed by edit file command (^KE). I've always used this facility for as long as I can remember and it never really occurred to me until now that people using more modern editors and especially GUI editors may not enjoy this same convenience--either not possible or no simple chain of command inputs to get there. And it's not like I don't use GUI editors, just not in situations where I would realize this feature was missing.