[Freeciv-Dev] Re: [RFC] Path finding interface

[Gregory Berkolaiko <Gregory.Berkolaiko@xxxxxxxxxxxx>]

On Wed, 10 Apr 2002, Raimar Falke wrote:

> On Wed, Apr 10, 2002 at 05:38:55PM +0100, Gregory Berkolaiko wrote:
> > On Wed, 10 Apr 2002, Raimar Falke wrote:
> > 
> > either I am very confused or you propose to return the whole path to each 
> > new accessible destination but you don't use anything but the last 
> > position.  Doesn't make any sense to me...
> 
> Yes it returns a whole path. We may shorten this to one position if
> this get speed. I made it this way to be consistent with the
> pf_get_path_from_map.

yes.  to get path (if you know you want it), just call the get_path 
function.

> > > > > provide provide iterators not only for one step but also for multiple
> > > > > targets. Just thing of this example: you have a settler which want
> > > > > itself to add to some city. You have the start position and multiple
> > > > > destinations on the same continent. You don't have to calculate all
> > > > > costs to reach all tiles of the continent. You may use the simple
> > > > > iterator but pf_get_path_from_map will do this for you.
> > > > 
> > > > how will get_path do it?
> > > 
> > > pf_get_path_from_map is an optimized version of:
> > > 
> > >   forever:
> > >     path=pf_get_next_path_from_map
> > >     if !path.is_valid: 
> > >       return path
> > >     if LAST_POS(path) == destination:
> > >       return path
> > 
> > that doesn't answer the question.
> > do you propose to stuff a list of destinations into pf_get_path ?
> > or supply it with a is_final_destination callback?
> 
> void pf_get_path_from_map(pf_map_t map, int dest_x, int dest_y,
>                           struct pf_path *path);
> 
> So the user just specify the destination by a map position.

Let's concentrate.
We are talking about multiple destinations which are fx cities or ports, 
or maybe even huts (location as yet unknown).  you say  
pf_get_path_from_map will handle it.  How?

> > I think just letting the "user" write the loop is much clearer and 
> > cheaper.  I tried it call-back way (terminating explorer search on 
> > discovering a hut), it didn't look pretty.

G.