Re: Should `revert-buffer' preserve text-scaling by default?

[Karl Fogel <kfogel@red-bean.com>]

On 02 Dec 2019, Eli Zaretskii wrote:
>> Even though Eli unconvinced me of that earlier, it turns out I'm
>> weak-minded enough to have already fallen back into thinking it's a
>> good idea now that you suggest it.  So I'm +1 on what you say, at
>> least until Eli posts again?
>
>If we use a special value of the argument, not just C-u, I'm okay with
>that (and I think I already said that in this discussion, didn't I?).

I think the first question is what the default behavior of `revert-buffer' should be -- after we decide that, we can decide what special prefix arg is used to access the non-default behavior.

Stefan proposed that the new default be to *not* reset modes, and that C-u could be reassigned to mean "and reset the modes".  Here is what he said:

>Currently, the revert-buffer's C-u is used to choose between "revert
>from file or revert from the auto-save file".  Personally I never use
>that (probably the most obvious reason is that I don't use auto-save
>files at all), so I'd gladly change this C-u to mean "and reset the
>modes".

To consider Stefan's proposal, we'd have to first decide that `revert-buffer' will no longer reset modes by default.  I had thought you were opposed to that change, on compatibility grounds.  But maybe you just meant that revert-buffer's `preserve-modes' argument should retain its current meaning when called non-interactively from Lisp, but that it would be okay for interactive `revert-buffer' to stop resetting modes by default?  In other words, the default interactive behavior could be changed to be the opposite of the default non-interactive behavior.

Was that what you were saying?

Regarding Stefan's proposal: I don't know how often people depend on the current C-u behavior of reverting from auto-save file.  But if we're changing the interactive default to not reset modes, then I think a special prefix -- different from C-u -- to access the old reset-modes behavior would be fine, partly because it would be rarely used!  Also, I presume we would have a new customizeable variable `revert-buffer-reset-modes' (defaulting to nil) that people who have a permanent preference could set.

Best regards,
-Karl