Re: NSDocument disc undo stack
Re: NSDocument disc undo stack
- Subject: Re: NSDocument disc undo stack
- From: Steven <email@hidden>
- Date: Mon, 26 Mar 2012 00:57:17 +0100
Thanks for the info Graham.
I'm using NSUndoManager. I thought that many large objects in the stack would cause memory pressure and would be better occupying disc space as they are only needed at undo/redo time. Good to know that the VM system will take care of it.
Steven.
On 24 Mar 2012, at 01:04, Graham Cox wrote:
> You can read and write to the Application Support folder.
>
> But FILES in an Undo stack? That makes little sense to me.
>
> If you want to undo changes to a file, store the changes or the command that will cause the changes in the undo stack. If you are changing the organisation of files on disc then save a description of that organisation in the undo stack. You may want to read up on the way Cocoa utilises Undo, because it sounds like you might not have a good grasp on it.
>
> Even if you need to store very large objects in the undo stack, unless you can prove it's a serious problem, just let the memory get paged to disk VM naturally. It's rare that users need to undo a very long history, so even if the older history is paged out, the chances are the user will never know.
>
> --Graham
>
>
>
>
>
> On 24/03/2012, at 10:17 AM, Steven wrote:
>
>> Hello,
>>
>> Where is the correct place to store an on-disc undo stack associated with a NSDocument instance ?
>> The stack may contain several potentially large files so we don't want them to occupy memory.
>> For a compound document the stack could reside in a directory NSFileWrapper.
>> For a single file document should a temporary directory be used ?
>> I guess the chosen location may need to persist beyond the occurrence of the automatic termination feature.
>> Any advice appreciated.
>> Thanks.
>>
>> Steven.
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