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[Freeciv-Dev] Re: [RFC] Caching AI values

[Freeciv-Dev] Re: [RFC] Caching AI values

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To: Gregory Berkolaiko <Gregory.Berkolaiko@xxxxxxxxxxxx>
Cc: freeciv-dev@xxxxxxxxxxx
Subject: [Freeciv-Dev] Re: [RFC] Caching AI values
From: Raimar Falke <hawk@xxxxxxxxxxxxxxxxxxxxxxx>
Date: Thu, 21 Mar 2002 08:15:14 +0100
Reply-to: rf13@xxxxxxxxxxxxxxxxxxxxxx

On Wed, Mar 20, 2002 at 07:16:37PM +0000, Gregory Berkolaiko wrote:
> On Tue, 19 Mar 2002, Raimar Falke wrote:
> > On Tue, Mar 19, 2002 at 08:36:02PM +0000, Gregory Berkolaiko wrote:
> > > 
> > > That might be right, but let's have a look at the overall picture:
> > > 1. Unit A thinks about moving to city C to kill things around.  The 
> > > number 
> > > of things to kill around C is calculated and recorded in struct city C.
> > > ----
> > 
> > > 2. we are doing other stuff, but whenever we kill a unit, we have to 
> > > figure out if it was counted in the targets_around_C and if it was, 
> > > subtract its value
> I thought this problem over and I got this great idea which, it seems, is 
> the same as you propose below (although I do not fully understand your 
> wording):
> If a unit is killed, we call a function which does not recalculate 
> anything by itself, but instead increments some "time" variable to show 
> that the cached values have expired.  Then, the next time we try to access 
> cached values, we will have to recalculate them.  This way we do not 
> recalculate anything that isn't going to be used and avoid all these 
> complex decisions "what to update" as well.
> Of course each type of cached values will have it's own "time" variable 
> associated with it.

This is known as lazy evaluation. You don't need a time field. A
simple bit "valid" is sufficient.


 email: rf13@xxxxxxxxxxxxxxxxx
 "How about the new language C&? No, that's not 'c ampersand', 'c reference', 
  'reference to c' or 'c and'. It's pronounced 'campersand', to confuse the 
  hell out of people who are unfamiliar with it, and it will, of course, 
  have no pointers."
    -- Xazziri in comp.lang.c++ about C#

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