Re: NSDocument disc undo stack
Re: NSDocument disc undo stack
- Subject: Re: NSDocument disc undo stack
- From: Graham Cox <email@hidden>
- Date: Sun, 01 Apr 2012 22:02:39 +1000
On 25/03/2012, at 5:34 AM, Doug Clinton wrote:
> I don't know if this was the issue that Steven was asking about, but I've been wondering if there is a recommended way to persist the undo stack so that it's still available if you restart the app, or close and re-open the document. It's always bothered me that there is this great mechanism for handling undo, but that all the history is thrown away when you close the app.
No easy way I know of. The undo architecture relies on a huge amount of state within the app external to the undo stack itself. You'd have to save all of that state somehow.
In fact, most apps throw away the undo history on a document save (you arrange this), as a way to recover the memory used by undo, since the whole state is being saved in the file anyway. Versions are the supported mechanism for persistent document undo.
--Graham
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