calculation control [Re: Linking to a stock market price feed.]

[Anthony Heading <aheading jpmorgan com>]

In the area of realtime external feeds, have the traditional
issues been catered for?

Jody wrote, in http://mail.gnome.org/archives/gnumeric-list/1999-June/msg00018.html :

%   One of the features that causes much grief is a lack of control of when
%   a function needs to be recalculated.  Specificly,
%    - a realtime data source will need to be triggered on external
%      inputs
%    - A function that has a stateful connection to a server will need
%      to be recalced when a sheet is loaded or an addin is reloaded.

and also then in response to me :

% > Well, there's one other issue that's important to me at least.  For
% > good performance, it's critical not to recalculate anything which is
% > not visible.  Some versions of Applix I think handle this quite well,
% > and it's conceptually pretty simple I think:   just ignore branches
% > of the calculation tree that don't lead to external IO (on-screen cells,
% > files, sockets, etc).
% 
% Applix 4.4.1 seems to have worked out most of the bugs but it took them
% several versions.  It is very important to be careful with this.  I've
% wasted much time chasing stochastic numbers resulting from incomplete
% recalculation.

It would be great if gnumeric were able to do this now.

Anthony



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