On 10/4/07, Phil Endecott <spam_from_boost_dev@chezphil.org> wrote:
Michael Marcin wrote:
Have a look at:
http://www.gamedev.net/community/forums/topic.asp?topic_id=261920
Yes, a very good page showing several solutions:
1. A vector of member pointers (may have some overhead). 2. Anonymous structs and unions (may be non-standard). 3. x, y and z implemented as references (makes object bigger). 4. Relying on (&x)[1] pointing to y.
For actual asm output, see http://www.gamedev.net/community/forums/topic.asp?topic_id=230443&PageSize=25&WhichPage=2 for the "overhead" of option 1.
_IF_ 4 really is guaranteed to work portably (as its author claims), it would get my vote:
template <typename T> struct point2d { T x, y; T& operator[](int i) { return (&x)[i]; } };
...what's the catch?
I'm almost positive the author was wrong in claiming that it is portable. Here's an old thread about the issue: http://groups.google.com/group/comp.lang.c++.moderated/browse_frm/thread/df5bc148a994d511/36c133bbb606bece?lnk=gst&q=point+operator%5B%5D+x+y+z&rnum=6#36c133bbb606bece --Michael Fawcett