p argument in undoer beforeXXX and afterXXX

[Brian Theado]

I added undo code to the ftlist code I shared in another thread (the code with undo implemented is here: https://gist.github.com/btheado/ca898b8b24b84ba08b3f26f61441cc41). 

The undo operations are working fine, but redo is giving me an assertion error.

It isn't clear to me what Position p are supposed to be passed into the undoer beforeXXX and afterXXX methods. Cloning and moving nodes are the only operations I have. For move, I assume I should be passing the position which is/was moved for both before and after. For clone, should I be passing the original before and the clone after?

My next step if I get a chance tomorrow will be to remove all of the operations but one to see if I can get undo/redo to work for a simpler case and then try to build up from there. I'm open to other ideas.

Here is the assertion error I'm getting on redo:

Traceback (most recent call last):

  File "/home/btheado/src/leo-editor/leo/core/leoGlobals.py", line 296, in new_cmd_wrapper

    func(self, event=event)

  File "/home/btheado/src/leo-editor/leo/core/leoUndo.py", line 1176, in redo

    u.redoHelper()

  File "/home/btheado/src/leo-editor/leo/core/leoUndo.py", line 1284, in redoGroup

    z.redoHelper(); count += 1

  File "/home/btheado/src/leo-editor/leo/core/leoUndo.py", line 1346, in redoMove

    assert u.oldParent_v.children[u.oldN] == v

AssertionError

Brian

[Edward K. Ream]

On Sat, Aug 17, 2019 at 10:09 PM Brian Theado <brian....@gmail.com> wrote:

It isn't clear to me what Position p are supposed to be passed into the undoer beforeXXX and afterXXX methods.

It's not clear to me either. I owe you, and all of Leo's users, an apology for writing such crappy, undocumented, code ;-)

The undo/redo group operations, which the traceback shows you are using, are particularly tricky.  My guess: there will be problems if the p arg passed to beforeUndoGroup doesn't match the p arg passed to afterUndoGroup. This makes sense: there has to be a stable point somewhere.

Edward