Re: Generic undo stack for GTK+

[Martin Nordholts <enselic gmail com>]

On 06/16/2010 10:01 PM, Holger Berndt wrote:
> Some time ago, there was some discussion about a generic undo stack in
> GTK+ [1]. The talk back then didn't result in more concrete API
> discussion. As undo/redo is part of the GTK+ Roadmap [2], I now shot
> ahead and created an undo proposal page [3] for that. Comments are very
> welcome.

I think it would be unfortunate to limit the generic undo mechanism to a 
stack, when full preservation of undo-version controlled data requires a 
tree:

4   7
|  /
3 5
|/
2
|
1

In the above tree, 4 revisions are created, then two undos are made, and 
then two new revisions are created from revisions 2. You don't want to 
end up with the undo stack


7
|
5
|
2
|
1

and lose 3 and 4.

Having a sane UI for this is a different matter, maybe most applications 
would only use the simpler stack based undo structure, but tree based 
undo apps should also be able to use the generic solution.

 / Martin



--

My GIMP Blog:
http://www.chromecode.com/
"Automatic tab style and removed tab title bar"