[boost] Re: a new version of geometry classes

From: mikewatkins (mikewatkins_at_[hidden])
Date: 2000-01-09 05:59:41

Hi I tried to use this but was unable to.  I do not seem to have #include
<cassert> could someone please send me this?

regards Mike

----- Original Message -----
From: Gavin Collings <gcollings_at_[hidden]>
To: <boost_at_[hidden]>
Sent: Friday, January 07, 2000 11:39 AM
Subject: [boost] Re: a new version of geometry classes

> > > Oh, here's another feature I like for my points: indexability (I like
> > > to be able to access the coordinates by index). That allows
> > > programmatic selection of orientation for things like scrollbars.
> > > Indexability is of course unusable when the types of x and y differ.
> > > OTOH this is definitely a corner case. I have no strong opinion on the
> > > topic.
> >
> > We can provide generic version of classes with two template parameters
> > (and without indexability) and a specialization for case T1==T2 with
> > operator[].  I think it will be reasonable solution.
>
> I have some sympathy with the overdesign comment, but it may be worthwhile
> considering the following for the generic version.  It overloads the []
operator
> and uses function overloading to achieve programmatic selection on
orientation
> etc.  Obviously, as it's a compile time thing, it can't be used for
looping over
> (x .. y) - but that shouldn't be a problem for just two coordinates.
>
>     struct x_coord {} x;
>     struct y_coord {} y;
>
>     template <typename X, typename Y = X> class point
>     {
>     public:
>
>        X operator[]( x_coord ) { return x_; }
>        Y operator[]( y_coord ) { return y_; }
>
>     private:
>
>        X x_;
>        Y y_;
>     };
>
>     class latitude  {};
>     class longitude {};
>
>     void process_coord( latitude )  {}
>     void process_coord( longitude ) {}
>
>
>     void test()
>     {
>        point<latitude, longitude> p;
>
>        latitude  lat = p[x];
>        longitude lon = p[y];
>
>        process_coord( p[x] );
>        process_coord( p[y] );
>     }
>
> Gavin
>
> --
> Gavin Collings
> gcollings_at_[hidden]
>
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