[Libreoffice] Calc - a better design ...

[Michael Meeks]

Hi Kevin,

On Thu, 2011-10-20 at 02:00 -0400, Kevin Hunter wrote:
> I'm hesitant to ask this because I cannot personally promise time toward 
> LO (only on an as-can basis, which is dismally small ATM), but hey, you 
> can easily so no.  :-)  You mention "really need[ing] a whiteboard" to 
> elaborate properly.

	That really helps; having said that - I sat down with Eike & Kohei to
discuss this in Paris, and (I hope) managed to communicate the essence
of the idea.

>   I submit that putting your thoughts together, perhaps in picture
> form and available on the LO wiki, or put together as a small video
> to Youtube, would be extremely useful to casual LO coders 
> like myself.

	Sure - so first off, since I'm not actively hacking on calc (as of
now), this is really not my call. I tried to persuade Kohei & Eike of
the intrinsic improvements possible with the new design - if I'm lucky
then they agree that I'm not mad & might think about that. Of course - I
can create a video too, but ... ;-)

>   As an individual volunteer without a face-to-face LO team 
> member against whom to bounce ideas, I'd thoroughly love an 
> actual-paid-engineer's thoughts on how best to proceed on this front.

	So - the very essence of what I'd like to see happen in calc, and the
foundation for it - is to remove the idea that a spreadsheet is a
collection of 'Cell' objects. This seems (to me) to be the foundation of
our scalability problems.

> I'm personally motivated for Calc because in my science career, I really 
> have to bend over backwards to make Calc work effectively for my needs 
> where Excel works just plain better/faster/smaller, yet I 
> philosophically have stuck myself with Free software.  To me, one of the 
> biggest areas of weakness for LO, after the various random crashes 
> (which are getting better!), is the memory bloat, and speed.  It's not 
> features.

	Right. So the biggest piece (I see) that need tackling here before we
can take advantage of the new code is to start restricting the scope of
'ScBaseCell' pointers in LibreOffice calc. Last I looked (which was a
while ago) we use ScBaseCell pointers all around the place for things
like undo/redo, change tracking, copy/paste, document construction etc.

	If you wanted to re-start the effort to remove ScBaseCell's mpNote
pointer (which is very infrequently used) - that'd be a great place to
see some of the problems: ultimately I think we want to remove
ScBaseCell (and it's derivatives) entirely - leaving a (numeric) cell as
a single 'double' inside a fixed column-array of entries of the same
type.

	Of course, even without the grand vision coming to fruition, saving 4
(or 8) bytes per cell would be worthwhile, and improving the above areas
to handle storage of ranges of cell contents in a better encapsulated
way would be rather valuable - I think.

	But of course, you really want to talk to Eike / Kohei / Markus.

> I'm happy to mess with Ixion (and indeed have poked at it some already)

	Right - IMHO, the real problem we have is not so much Ixion (which is
great), but massaging the existing code into a good shape to be ready
for it's heart transplant ;-) The above would be a great step in that
direction.

	Of course, if the calc developers don't object, I'm happy to create a
video of me making a fool of myself with a whiteboard too if you think
it helps :-)

	All the best,

		Michael.

-- 
michael.meeks at suse.com  <><, Pseudo Engineer, itinerant idiot