Re: [Lib2geom-devel] Geom::Point coordinate access

[Johan E. <jbc...@sw...>]

On 17-6-2011 22:49, Krzysztof Kosiński wrote:
> Hello all
> I'm writing an integer rectangle class which I will use in my GSoC
> project, and since i need to also introduce integer points, I would
> like to ask for your opinions about one thing related to all points:
> Currently Geom::Point has the index operator as the only way of access
> to the coordinates. However, this is often inconvenient, especially
> when Geom::X and Geom::Y, and leads to hard to parse notation like
> (a-b)[Geom::Y]. Here are the proposed solutions:
>
> 1. New methods
> Coord&x(); Coord&y(); + const versions
> This is OK, but I don't see much merit in having the extra parentheses
> of a method call, since there is read-write access to the coordinates
> anyway.
>
> 2. Public members in a transparent union
> union { struct { Coord x; Coord y; }; Coord _pt[2]; }
> Might not work on some compilers.
>
> 3. Replace _pt with public members
> Coord x, y;
> Could theoretically be lower performing, because we now have to use an
> if for indexing, but in reality on anything more modern than Pentium
> Pro both the if and the table access will be compiled to conditional
> moves.

I assume in option 3 that you keep operator[] ? I agree that [Geom::Y] 
is extremely annoying and much too verbose.

Ciao,
Johan