On 17/12/2009, at 7:13 AM, Scott Squires wrote: > Is there a clean method (which I take it is the group method) to make sure > that undo functions aren't automatically grouped based on event cycles? Is > there a recommended way of dealing with UI and async actions relative to the > undomanager?
To turn off automatic grouping, call -setGroupsByEvent:NO. You'll then be responsible for opening and closing the top-level group yourself. You must do this - having no group open is an error. You must submit all your tasks to the undo manager on the main thread. Even so, I imagine you'll run into problems, because your thread is not running in any way synchronised to the main event loop - therefore you may end up with some tasks in one group and others in another depending on what is happening on the main thread with undo coming from elsewhere. Personally I'm not sure that can be reconciled. It might be better if your thread can prepare some object which sets an undoable property on the main thread in one go when it's done, rather than attempt to submit individual tasks to the undo manager. I just don't think it's designed to handle that situation (in fact I know it's not) and you'll end up doing a crazy amount of work to make it operate sanely. > You imply that there are undomanager issues. Are there known ones I and > others should be aware of? The main problem is that it's not a solution for every possible Undo need, so where your requirements are slightly off the norm, it's often a lot of work to bend it to your will. It's also a black box with a large private API and internal structure unpublished, undocumented and difficult to override or figure out what's happening when it's not co-operating. For the most straightforward, single main-event-loop based Undo, it's great. 80:20 rule applies - if you're in the 20% though, it can be painful. I outlined some of the rationale I had for writing my own Undo class on my website: http://apptree.net/gcundomanager.htm --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
