Re: [Toon-members] Problem with const correctness fix/Jan 11, 2010

[E. Rosten]

On Mon, 18 Jan 2010, Ville Kyrki wrote:

> Hi,
>
> I've been passing a slice to SO3::exp() as a parameter
> and the const correctness fixes on Jan 11 seem to have
> broken that.

OK, it is fixed now. Unfortunately, it is not possible to get C++ to do 
quite the right thing with regards to const. The old solution yielded 
undefined behaviour. The new one requires a little more care with 
implementation, so I expect for the odd bug like this to crop up now and 
again until they're all fixed.

> Example:
>
> void foo(TooN::Vector<6>& v)
> {
>         TooN::SO3<double>::exp(v.slice<3,3>());
> }
>
> is broken currently (I don't know if it's supposed to work,
> but it did earlier). slice can be of course avoided with a
> temporary vector, but using slice would make things nicer.
>
> I'm not sure, but it seems to me that the fix would need
> to be made in so3.h, although SO3::exp was already
> parametrized with the precision parameter (as suggested
> in the comment to the const correctness fix):
> template <typename Prec>
> template <int S, typename VA>
> SO3<Prec>::exp(const Vector<S,Prec,VA>& w)

The problem is that the SO3 class is templated, but not the member 
function. That has changed now.

-Ed

--
(You can't go wrong with psycho-rats.)(http://mi.eng.cam.ac.uk/~er258)

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