[freeciv-ai] Re: [Freeciv-Dev] (PR#6293) pf iterator design woes

["Raimar Falke" <i-freeciv-lists@xxxxxxxxxxxxx>]

On Mon, Oct 20, 2003 at 02:02:55AM -0700, Per I. Mathisen wrote:
> 
> On Mon, 20 Oct 2003, Raimar Falke wrote:
> > Mixing these two for one map is possible but not encouraged. I would
> > even go this far to disable it i.e. after your first call to
> > pf_get_position you can't use pf_next and the other way around.
> 
> This is a possibility which is better than the current solution, which is
> bug prone.

So you would accept this? Also as a minor implementation change I
would add the type P_ITERATE vs P_QUERY to the parameters.

> > > Say you pf_next() for a short-term attack target, and then find something
> > > that looks promising, but before you make this decision, you just want to
> > > know how far you are from your long-term target. Calling pf_get_position()
> > > on this long-term target will likely screw up the iterator. So you must
> > > create a second pf map to find this information. This is bug prone and
> > > slow.
> >
> > If this is _really needed_ (please think hard about it) we have to
> > redesign the PF code. However for this you first have to describe the
> > semantics you want.
> 
> It is also possible to add a cache layer on top of pf. I have written
> this, but I believe it is too slow.
> 
> > You want that pf_next and pf_get_position are independent?!
> 
> I don't understand what you mean by independent. It would be nice if we
> could use them interchangably, but it is not critical. It is worse that we
> cannot traverse the same pf map twice, but this is also not critical. Or
> at least that is what I think right now. I might change my mind some other
> day ;)

AFAIK the new PF is still not used in all places of the AI. Is this
correct? If we have a reasonable usage base we can start optimizing
PF.

        Raimar

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