
Boost : 
From: Geoffrey Irving (irving_at_[hidden])
Date: 20060920 12:59:08
On Wed, Sep 20, 2006 at 05:48:55PM +0100, Olivier Grant wrote:
> Hi,
>
> I agree, but between writing this :
>
> class vector3d
> {
> public:
> typedef float coordinate_type;
> typedef integral_constant<unsigned int, 3> dimension;
>
> vector3d( coordinate_type _x, coordinate_type _y, coordinate_type _z )
> : x(_x), y(_y), z(_z)
> { }
>
> coordinate_type x, y, z;
> };
>
> and this :
>
> template< typename coordinate_type, unsigned int dimension >
> class vector;
>
> template< >
> class vector<float, 3>
> {
> public:
> vector( float _x, float _y, float _z )
> : x(_x), y(_y), z(_z)
> { }
>
> float x, y, z;
> };
>
> I can't really see the difference apart from the syntax. both ways you can
> determine the number of coordinates and their type, which is whay is
> necessary to be able to write generic code that can manipulate vectors
> whatever their coordinate. I think the interesting part of my code is the
> implementation that does this abstraction, not the class implementation.
The difference is that if you have an int and a T lying around, vector<i,T>
lets you convert it into a vector type easily, and vectoriT does not. As you
say, the only possible advantages to vectoriT are syntactic, so you might as
well use the more flexible scheme.
Geoffrey
Boost list run by bdawes at acm.org, gregod at cs.rpi.edu, cpdaniel at pacbell.net, john at johnmaddock.co.uk