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Re: UNDO and Mathematica - how useless is it?

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  • Subject: [mg98023] Re: UNDO and Mathematica - how useless is it?
  • From: Bob F <deepyogurt at>
  • Date: Sat, 28 Mar 2009 05:42:21 -0500 (EST)
  • References: <> <23582715.1238067049865.JavaMail.root@m02>

On Mar 27, 4:33 am, "David Park" <djmp... at> wrote:
> I think that some, at least, of the important WRI developers do take noti=
> of what is on MathGroup. So give detail and make a good case and I think
> they will consider it. They may not necessarily do it because it may be
> difficult, but there are a number of changes I've seen that did appear to
> come from MathGroup complaints and suggestions.
> David Park
> djmp... at comcast.net 

I agree that the definition of what UNDO means can be problematic with
Mathematica, but if you talk about only the editing of the notebook
itself with regard to UNDO, then it becomes much easier, doesn't it?.
If we only talk about the editing changes of a notebook wouldn't the
UNDO be trivial to implement?

For any sort of calculations just put in different data and re-execute
the notebook or cell.

Part of each cell definition is a timestamp (look at the low-level
code by doing a Cell/Show Expression if you want to see). With this
information and some sort of keyboard input data structure going back
in time any number of levels would be just a question of undoing that
level of keyboard input and go back to the previous version of the
text wouldn't it, then a simple re-execution of the cell gets you back
where you were?

It seems that because the problem is difficult to provide a "perfect"
solution, the currently worthless solution is any better?

What would be bad about providing an UNDO that only worked on the
state of the text that forms the notebook or cell? That way any change
could be undone, and if needed then a simple re-execution of the cell/
notebook would get the old calculation back. Yes, I realize what about
if the calculation took 4 days to complete, you surely dont want to
undo that if the result is truly valid, but perhaps a cell could be
marked as "Don't Change with UNDO" or something like that (just like
you can mark it as visible or editable or ???) Would this give people
all the ability of a multi-level undo without the possibility of
loosing valuable calculations??

Would someone at Wolfram PLEASE comment about the state of the UNDO
debate and what is and isn't possible and what the various problems
with certain solutions are???


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