Re: [Boost-users] [uBLAS] Predefined subrange or project

9 Mar 2011

      On 09/03/2011 17:11, Ryan wrote:
...
On Wed, Mar 9, 2011 at 4:09 AM, Mathias Gaunard
mailto:mathias.gaunard@ens-lyon.org> wrote:
On 09/03/2011 09:59, sguazt wrote:
namespace ublas = ::boost::numeric::ublas;
template<typename MatrixT>
        inline
        ublas::matrix_range<MatrixT>  topleft(MatrixT&  M)
        {
           return ublas::subrange(M, 0, 3, 0, 3);
        }
You might want to provide a const overload as well.
Why would I want a const overload?  I want to be able to change the
values in the matrix passed to the function.
To allow rvalues and propagate constness, so as to make it behave more 
like a typedef or macro.

In the snippet you gave, of course, it needs to be non-const. But it's 
good practice to provide both when you write such adaptors.