Re: INDIRECT and real-time question

[Pavel Shevchenko <pavel telemetry-investments com>]

Jody Goldberg writes:
 > Area based is definitely a requirement, my initial thought was an
 > array formula based approach.
 > 
 >     with record ids in A2:A101
 >     with field ids in B1:F1
 >     select B2:F101
 >     =ReadFromFeed(feedID,A2:A101,B1:B1)<Ctrl-Shift-Enter>
 >  
 > On the positive side you get appropriate permisioning on the cells.
 > They would not be individually editable, and the recalc would be
 > enmass.
Sometimes it is not desirable. For example if I stop receiving data
for some symbol from feed I should be able to insert it manualy. 
It really happens all the time.

 > 
 > There are 2 downsides
 > 1) Changing the size of the array is cumbersome.
 > 2) With a naive approach when one of the values change, anything
 >    depending on all of them would recalc.  However, that can be
 >    circumvented by being a touch smarte w.r.t. how to handle the
 >    updates.  If we change the corner cell value directly and queue
 >    the individual update cells directly things will work nicely.
Naive approach will not work. In my SNP500 example there are 12-13
updates per 0.5 second (I found that half second is the best update
interval for user perception) out of 500 symbols. 
 > 
 > Update interval
 >     The current approach of recalculating as updates come in
 >     is destined for starvation.  A better approach would be to
 >     queue the changes for an interval, then commit in a block
 >     and recalc.  This should be simple to implement, all that would
 >     be required would be an interface to control frequency
It will be nice to have some sort of user defined dialogs. So I should be able to
register my own dialog called from say "Plugins config" menu. It can be part of XML
plugin description.

Pavel.