bugPSPP - Bugs: bug #24801, No undo function

 
 

bug #24801: No undo function

Submitter:  None
Submitted:  Mon 10 Nov 2008 02:26:55 PM UTC
   
 
Category:  Graphical User Interface Severity:  1 - Wishlist
Status:  None Assigned to:  None
Open/Closed:  Open Release:  Future
Effort:  0.00
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Tue 11 Nov 2008 03:11:06 PM UTC, comment #6: 


>should there be an undo stack per dataset, or one undo stack for
>the whole application?
>
>I think the latter.


My text editor has one undo stack per file, and this seems very natural to me.  Can you explain why you think that one global undo stack is more natural?

I expect that each data set will have its own top-level window.  Is that also your expectation?  In such a case, it seems to me that selecting "Undo" from one window and having a different data set change would be surprising.

Ben Pfaff <blp>
Group administrator
Tue 11 Nov 2008 11:30:46 AM UTC, comment #5: 

A seperate issue is how undo should behave with multiple datasets.  That is to say, should there be an undo stack per dataset, or one undo stack for the whole application?

I think the latter.  In which case, each layer in the stack needs to contain not only a list of datasets.

John Darrington <jmd>
Group administrator
Mon 10 Nov 2008 10:21:07 PM UTC, comment #4: 


>As I recall, what spss does (did) was to allow multiple levels of
>undo, until an EXECUTE happens, at which point the stack is
>emptied and one cannot undo anything.


We should be able to match that, at least, although it will take some work.

Most procedures don't modify the data set, so it would also be possible to extend the undo past those procedure.

Ben Pfaff <blp>
Group administrator
Mon 10 Nov 2008 10:12:20 PM UTC, comment #3: 


> The cost, at most, would be doubling the memory and disk requirements (for a single level of undo).


The single level qualification is of course pertinent.  I was thinking of allowing multiple levels.

As I recall, what spss does (did) was to allow multiple levels of undo, until an EXECUTE happens, at which point the stack is emptied and one cannot undo anything.

John Darrington <jmd>
Group administrator
Mon 10 Nov 2008 10:00:52 PM UTC, comment #2: 


>I can't think of any general and efficient way to undo the effect
>of an EXECUTE command.


General and efficient?  Me neither.  But it would be pretty easy to undo it in a general way, by keeping around the old casereader.  The need to preserve other parts of the dataset (e.g. dictionary) make it slightly nontrivial, but still it wouldn't be that hard.

The cost, at most, would be doubling the memory and disk requirements (for a single level of undo).

Do we run EXECUTE after every operation?  We wouldn't necessarily have to do that; for example, most transformations can be simulated on a per-case basis.  But that would not be a simple change (even though it would be convenient for users).

Ben Pfaff <blp>
Group administrator
Mon 10 Nov 2008 09:53:13 PM UTC, comment #1: 

This has been in the back of my mind for a while.

Although simple actions could be undone, I can't think of any general and efficient way to undo the effect of an EXECUTE command.

John Darrington <jmd>
Group administrator
Mon 10 Nov 2008 02:26:55 PM UTC, original submission:  

There's no way to undo any action in psppire.

Anonymous

 

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    Follow 2 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2011-05-14 blp ReleaseNone Future
    2008-11-10 jmd Severity5 - Average 1 - Wishlist

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