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From: Michael Fawcett (michael.fawcett_at_[hidden])
Date: 2008-05-01 12:17:14

On Thu, May 1, 2008 at 8:41 AM, Bruno Lalande <bruno.lalande_at_[hidden]> wrote:
> The point concept of Barend's library doesn't require any x() or y()
> member functions. The fact that the library proposes 2 predefined
> point classes, point_xy and point_ll, can be a bit confusing but don't
> be fooled: they do *not* represent the point concept, they are only 2
> classes that satisfy it. The point concept uses accessors of this kind
> :
> template <int I> value() const;

Could you just specialize boost::get?

> In the second preview of the library, there was also runtime indexing
> accessors, but they should disappear to only have compile-time
> accessors as shown above (I'm currently working on this with Barend).
> Also, the point concept as currently defined might be replaced by a
> point_traits class usable the same way as what you propose with your
> point_interface<T>. It gives something like :
> point_traits<T>::value<0>(p) to have the first coordinate of a point
> p. The point concept would then follow the exact definition just given
> by Phil. Not sure yet this will be done, but it brings a lot of
> advantages (non-intrusiveness, possibility of using native arrays as
> points, ...).

That's a very big advantage. What about using boost::tuples?
boost::get gives you these things with a common syntax. I believe
that ideally, the compile-time indexable point concept should support
the boost::get syntax, and the run-time version (for looping over
members) should support array access.

--Michael Fawcett

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