Make the free function 'size' support the uBLAS traits system and better work with expression types

[Marco Guazzone <marco.guazzone@…>]

Actually the implementation of the size free function has two weak points:

1. It does not make use of the new uBLAS traits system introduced by Gunter.
   E.g.: typename ExprT::size_type should become typename matrix_traits<ExprT>::size_type

2. It does not fully support expression types. The current support is error prone and not user-friendly.
   E.g.: if ExprT is an expression type and e is a variable of type ExprT, then one has to call size(e()) instead of simply size(e).

I suggest to change the size operation in order to fix the above issues.

[Marco Guazzone <marco.guazzone@…>]

Adds the use of uBLAS type traits, simplifies the interaction with expression types, replaces the 'size<tag>' function with the 'size_by_tag<tag>' function.

[Marco Guazzone <marco.guazzone@…>]

I've tried to change the 'size' operation without affecting its syntax but I've failed.

More specifically, the problem is given by one of the polymorphic version of size:

    template <typename TagT, typename ExprT>
    typename ExprT::size_type size(ExprT const& e);

which I've initially transformed into

    template <typename TagT, typename MatrixExprT>
    typename matrix_traits<MatrixExprT>::size_type size(matrix_expression<ExprT> const& me);

See the thread ​http://lists.boost.org/MailArchives/ublas/2010/06/4362.php for more details.

So, my solution is to break back compatibility by removing that version of size and introducing a new free function (e.g., size_by_tag) with the same semantic.

I attach a patch for the size operation and the related test suite.

[Marco Guazzone <marco.guazzone@…>]

Patch for size.hpp which is back compatible.

[Marco Guazzone <marco.guazzone@…>]

At the end I was able to create a patch for size.hpp which does not break back compatibility. So ignore the initially submitted patch (size-allow_expr_and_break_back_comp.patch).

I admit the real credits go to Daniel & Stefan, two guys that suggested to me the way to go. For more info see: ​http://groups.google.com/group/comp.lang.c++.moderated/browse_thread/thread/bd5080b28865f826

Summary of changes:

• Use of ublas type-traits system (e.g. typename matrix_traits<M>::size_type).
• Explicit use of matrix_/vector_expression in function arguments (e.g. size(matrix_expression<M> const& m).
• Call to size<1>(v), with v a vector expression, is legal and returns the length of the vector-
  Do you like it?

[anonymous]

patch applied and commited in trunk