Re: Undo capabilities on top of EOF
Re: Undo capabilities on top of EOF
- Subject: Re: Undo capabilities on top of EOF
- From: Florijan Stamenkovic <email@hidden>
- Date: Mon, 28 Jan 2008 13:42:00 -0400
Hi Ken,
On Jan 27, 2008, at 16:11, Ken Anderson wrote:
Florijan,
You can always look at see what EOF puts on the undo stack for
whatever operation you want to undo - that would be the easiest way
to identify the 'right way' to undo things.
Uhm, how do you suggest I do that? Are you talking about somehow
extracting EOF operations from the NSUndoManager?
One of the problems is that (from what I've heard) the NSUndoManager
tends to screw up. I've never tried using it though, so it could be
just slander. Are you using it successfully?
Is this just an exercise? Do you have a goal for wanting to use
something other than NSUndoManager ?
Ideally, I would like to build the undo support for editing records
on top of the JBND library, which abstracts from EOs into the
DataObject interface (see http://web.mac.com/flor385/JBND/api/org/
jbnd/DataObject.html). That would only work if the editing of EOs can
for all kinds of properties be undone by simply applying reverse
operations on the EO. This would be cool because JBND has an event
and notification firing system I could very easily plug into. So,
assuming that editing (relationships worry me) can be handled this
way in EOF, this solution would be easier and more applicable, in my
situation, then starting to deal with NSUndoManager.
Then I'd implement undo support (that would have to be EOF specific)
for record adding and deleting, if that is possible, and provide that
with the EOF package of JBND.
Then I'd implement GUI level undo support, and wrap that all up in
our Swing application to provide complete undo / redo support for
virtually every user action. Then my brain would probably become
spaghetti, but hey, the boss would be happy :)
Flor
Ken
On Jan 27, 2008, at 2:03 PM, Florijan Stamenkovic wrote:
Hi all,
Here's a question: has anyone ever tried implementing undo / redo
support for EOF, that is not based on the NSUndoManager? Or, can
one estimate if it is even possible, I am just trying to think
about the possibilities and pitfalls... Here are a few specific
questions:
1. Inserting records, then un-inserting and re-inserting them...
Could the same EOs be used? Would the ec flip? Would the object
graph roll back to the same state, regardless of the deletion
rules of relationships of the inserted object?
2. Same questions about deleting records.
3. Could relationship editing be undone and redone by simply
applying reverse actions? Would EOF accept that without problems?
Would it be better to simply ignore insertion and deletion, and
focus only on the editing? Anything else that might be a problem
that I've missed?
Thanks for any thoughts,
Flor
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