It's not just me running into undo problems - ironically just got this from Xcode (requiring quit and relaunch to recover) while trying to build after tweaking my undo manager source:
"Internal error occurred while creating dependency graph: _registerUndoObject:: NSUndoManager 0x3befcb10 is in invalid state, must begin a group before registering undo". (Why it needs to register with Undo while building the dependency graph is another question - it's not as if you can undo that or would want to). On 07/12/2009, at 7:00 AM, Quincey Morris wrote: >> I tried it but it doesn't work. I forget the details now as this was my >> first approach and that was a long time ago, but basically the undo manager >> didn't tolerate having groups deferred until a task was actually received. >> It would crash, but without the code, I couldn't say why . > > I'm not sure I understand this point. Are you talking about a situation with > 'setGroupsByEvent:YES' or 'setGroupsByEvent:NO'? Either way, an explicit call > to 'beginUndoGrouping:' is *by definition* deferred, since it obviously can't > happen the instant an event is dequeued. The length of time between dequeuing > an event and invoking an undo manager method seems irrelevant. But I ask > mainly out of curiosity because ... I think my understanding of how groups by event works was shaky at the time, so it's possible that I did something silly. Quite likely in fact. The deferrment was in a subclass of course, and it was in the situation where groupsByEvent was NO, and I wanted to group a bunch of drags. I set a flag on -beginUndoGrouping but did not call super. Then when a task was received from a drag change, if the flag was set I called super's -beginUndoGrouping "just in time". That's when it crashed if I recall correctly. >> An undo manager collects all undo operations that occur within a single >> cycle of the run loop, so that performing an undo reverts all changes that >> occurred during the cycle. > > Taken literally, that would seem to say that NSUndoManager's API contract > doesn't support undo actions that span events. FWIW. Yes, which does make me wonder how others have implemented undo of drags in general. Is there a simple solution staring me in the face and I just can't see it? I think I'm in a drag-induced stupor, but if I can get this to work elegantly perhaps I could be a drag artist ;-) --Graham _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
