> Neither one has been reimplemented in other software, and it would be extraordinarily difficult to actually do that, because of all the specificity and quirks.
Why is this a problem? That's like saying "I need a good GPU to run this game, this sucks!" Well, no shit I guess?
And it's not even close to that because you can always just buy/compile/compile the right version. And for darktable you don't even need that, backward compatibility is guaranteed. Also darktable has a rudimentary Lightroom to darktable conversion tool (never used it).
> This is more complexity than most people ordinarily expect when they talk about "backing up photos", and that's exactly my point.
Not sure about the other ones, but for darktable, it's as simple as keeping the XML alive.
> I explained a very specific issue: that there's a lot of complexity to developing raw photos, which means you have to take extra steps to make sure your edits are properly backed up. Open source software has a distinct advantage because you can archive a copy of the software yourself, but it doesn't change the fact that you do need the original software. And in fact you might need the same version, that's what the example of DNG conversion is supposed to illustrate.
If you don't like having a non-destructive copy, save a high quality JPEG with your edits. Also, I can't think of any other applications (not just photo editing) that you can easily have future-proof non destructive copies of whatever you need to save.
For example: for audio, you can always just save a WAV or FLAC of your work, but you're still relying on the fact that your DAW workflow is still gonna exist 10 years in the future if you try to save your project as opposed to a mastered copy.
Code is also similar. You can save a binary which will probably work, but if you want to save your repo, unless it has good package managers you might have issues later down the line, like that left-pad incident a while back.
Hell, even for something completely different: language drifts over time, and reading Shakespeare is kind of hard unless you know how to read Middle English. And we don't seem to have a problem with forward compatibility, it's just a bit of a pain in the ass. I read it in High School and I didn't go insane.
This isn't a photography issue, this isn't a software issue, this is a core part of human experience.
> This is ... the opposite of a non-issue. In fact it's a very specific issue that I took quite a bit of time to explain in detail. Having to back up your software, or possibly even an entire VM along with your photos to make sure your edits are preserved, goes way beyond what your average person, or even many photographers think they have to do to keep proper backups.
You don't need a VM, at least for darktable. You're making an issue that hasn't appeared but is potentially possible into a real issue for yourself. Maybe it will become an issue, but just figuring out how to install the old version is gonna be good enough. You do you mane. I'll stick with running dt natively and trusting the forward compatibility and OpenCL acceleration.