A critic of Guido's blog on Python's lambda

[Ken Tilton]

Thomas F. Burdick wrote:
> Ken Tilton <kentilton at gmail.com> writes:
> 
> 
>>No, you do not want on-change handlers propagating data to other
>>slots, though that is a sound albeit primitive way of improving
>>self-consistency of data in big apps. The productivity win with
>>VisiCalc was that one simply writes rules that use other cells, and
>>the system keeps track of what to update as any cell changes for
>>you. You have that exactly backwards: every slot has to know what
>>other slots to update. Ick.
> 
> 
> No no, that's fine and the way it should be: when you change a slot,
> it should know who to update.  And that's also the way it works in
> Cells.  The trick is that Cells takes care of that part for you: all
> the *programmer* has to care about is what values a slot depends on --
> Cells takes care of inverting that for you, which is important because
> that's a job that a computer is much better at than a human.

Well, as long as we are being precise, an important distinction is being 
obscured here: I was objecting to a slot "knowing" who to update thanks 
to having been hardcoded to update certain other slots. When you say 
"Cells takes care of that", it is important to note that it does so 
dynamically at runtime based on actual usage of one slot by the rule for 
another slot.

kt

-- 
Cells: http://common-lisp.net/project/cells/

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