[Freeciv-Dev] Re: the directional system

["Ross W. Wetmore" <rwetmore@xxxxxxxxxxxx>]

At 08:50 AM 01/09/07 -0400, Jason Dorje Short wrote:
>Raimar Falke wrote:
[...]
>One other clarification: I've removed the DIR_D[XY]2 arrays, but I've
>changed the DIR_D[XY] arrays to use that directional system so really
>it's everything else that has changed.  Trying to find magic code by
>searching for DIR_D[XY] usages is pretty futile; the use of DIR_D[XY]
>itself is quite safe but the problem is when the code tries to
>manipulate the directions directly.  This often occurs several levels
>down (for instance in straightest_direction() and get_char() which don't
>use the arrays at all).  So, it will be difficult to tell by inspecting
>the code that all "magic" has been removed.

This is worth repeating ... people need to understand, and so far I think
too few actually do.

Actually, there are two points here. Changing DIR_DX under the covers
can cause lots of problems, because you really don't look at each case
where it is used when you just change the semantics/data - the existing
code has not really been cleaned to use a standard approach where such
changes can be done. Also, there are lots of places that assume things 
about directions and magic numbers or algorithms like 7-dir.

>jason

Cheers,
RossW
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