Subject: Re: bug#77580: [PATCH] New command ediff-undo

From: Sean Whitton <[email-masked]>
Date: Fri, 11 Apr 2025 18:40:35 +0800

Hello,

On Thu 10 Apr 2025 at 04:42pm +02, Michael Heerdegen wrote:

> Hello,
>
>>   M-x vundo, m, b, d, q, C-x b *vundo-diff<TAB>.
>>
>> These ergonomics scale nicely when exploring undo histories, but for
>> quick comparisons, they're hardly better than "fully manual" (copying
>> to a temp buffer and doing diff-buffers).
>
> My main concern is whether your proposed interface is really convenient.

I was about to write pretty much the same thing: I think that these
commands are not yet fully baked.  I think that they are too difficult
to use.

The problem is, it seems too difficult for the user to know what prefix
argument to supply.  We don't keep a count of buffer changes in our
heads so that we could know how many changes back we need to go to get a
diff that will contain the information we want.

In fact, showing a diff for a given number of undo operations backwards
seems more like a function to be called from Lisp than an interactive
command, because Lisp could calculate the number of operations to go
back, somehow.

If there is a more minimal version of vundo that is accessible and
generally useful, we haven't found it yet.  It's fine if this takes some
time, we can keep the bug open and let the ideas simmer and come up with
something really good.

-- 
Sean Whitton