[Freeciv-Dev] Re: Map coordinate cleanups.

[Trent Piepho <xyzzy@xxxxxxxxxxxxx>]

On Fri, 17 Aug 2001, Raimar Falke wrote:
> I have to admit I haven't learned the difference between proper and
> normal during my coding. Maybe I have used too much copy and paste. I
> think there should be the following sets of positions/tiles:

proper is some new thing Gaute came up with.  So you haven't seen it
before.

>  A = the base set of all possible positions
>  B = the set of real positions: a real position is a position which have
>  directly or indirectly a tile associated with it
>  C = the set of normalized positions: each tile has exactly one
>  normalized position associated with it
>  D = A minus B = the set of unreal positions
>  E = B minis C = the set of unnormalized positions
> 
> B is a subset of A. C is a subset of B. Depending on the topology
> these are subsets or proper subsets.
> 
> The following methods are declared:
>  - is_real_position(p) tests if p is in B
>  - is_normalized_position(p) tests if p is in C
>  - p'=normalize_position(p) p must be in B, returns the normalized
>  version of p

That is what makes the most sense to me too.  It's also what I've understood
to to be the existing code all along now.  The function is_real_tile() already
exists, and is_normal_tile() has been in some patches for quite a while.

What Gaute has done is make it so that C is no longer a subset of B, as it
includes non-real positions in the normalized form.  Then he defined a fourth
set, he called proper, that is the same as your set C.  There are still the
same two useful subsets of A, now called real and proper, and one new useless
subset called normal.