Re: [eigen] Best practices for accessing named regions within a larger array?

[Gael Guennebaud <gael.guennebaud@xxxxxxxxx>]

Hi Rhys,

I'm not sure to understand your issue. Do you have a concrete example
of the "error-prone boilerplate" you are talking about?

cheers,
gael

On Tue, Nov 22, 2011 at 12:05 AM, Rhys Ulerich <rhys.ulerich@xxxxxxxxx> wrote:
> Hi all,
>
> I keep running into use cases where I'd like to have a contiguous
> array cut up into "named" subarrays of varying widths.
>
> As a simplistic example, say I want Array<double, Dynamic, 5> to have
> the leftmost column named "rho", the next three columns named "rhou",
> and the final column named "rhoe".  That is, I'd like I'd like
> foo.rho() to mean foo.leftCols<1>(), foo.rhou() to mean
> foo.middleCols<3>(1), and foo.rhoe() to mean foo.rightCols<1>().
> Having named regions within contiguous storage happens to be handy
> within my simulation code for both memory access patterns and
> readability purposes.
>
> Accomplishing this by using either inheritance or containment of an
> Eigen::Array instance and then adding inlined members is
> straightforward, of course.  But both requires error-prone boilerplate
> if the number of named views becomes large.  That error-prone
> boilerplate can be traded for macros (a la Boost.Preprocessor) at the
> expense of readability.
>
> I've not yet found a simple, clean, extensible way to produce such
> views methods.  Any suggestions or solutions that you've found
> elegant?
>
> Thanks,
> Rhys
>
>