[Oberon] Re: Power-down restoration

[John Drake]

From: Chris Glur <easlab at absamail.co.za>

> BTW my motive for origniation this topic was NOT how
> to restore after an unintended power-down; but how to
> be able to restore to not lose the work-continuity [especially
> to mental model of where all the pieces are located] after
> an intentional 'soft-landing'. It's about energy saving.

System 3 in general supports a persistent desktop idea.
I assume N.O. does the same.  Assuming each document
you had opened has been saved it will bring you back to
where you were.  But that's for the S3 windowed environment
only.

> AFAIK for N-O all that needs to be saved is the display details.
> Other globals like search & replace strings don't need to be saved.
> I guess the set of loaded modules, will just be individually reloaded
> on demand ?

That's probably how the persistent desktop works.

> My idea of how such a project would evolve [by successive refinement,
> is:---

> Find the root of the User & System display tree, either from a given
> global, or by linking up towards the root from a visible frame.

> Trace [output] the Frame labels while linking.

> A possible spin-off might be the easy ability to:
> 1. list the total set of frames,
> 2. select one to be 'moved to the "top" '
> 3. rearrange the links accordingly.

> Coming down from the root, would include all the embedded gadgets
> too.

> Then the mapping of the DisplayFrame contents to the heap would 
> need to be saved too. 

> Perhaps if you just saved the heap and the stack-frame-sequence,
> that would remove the need to save pieces.

> This is a non-trivial task !?

> == Chris Glur.

It certainly sounds doable.  But I suspect you'd have to rebuild the
kernel.