Re: [Boost-users] templated class member

Ares Lagae ha escrito: [...]

I was wondering, however, if variable_list_member can be eliminated, and my_type passed as a template argument. E.g. suppose I write a metafunction

template <typename T> struct my_type { typedef /* some type */ type; }

to somehow declare

typedef variable_list_seq, my_type> vl_type;

to obtain a variable list with "keys" int, char, double and variables of type my_type<int>::type, ....

Yep, this can be done adding an optional template parameter to variable_list_seq, as shown in the example attached. Note that variable_list_member is not elminated, but merely supplemented with your my_type metafunction so as to be able to customize member types.

2/ would it be possible to generated variables my_type for all possible combinations of T1 and T2, where T1 and T2 are types in two typelists?

Something like

typedef product_variable_list_seq, boost::mpl::vector<...>, my_type> vl_type;

where my_type is a

template struct my_type { typedef /* some type */ type; }

Again, starting from the simpler variable_list_seq one can write a new product_variable_list_seq working on the cartesian product of two MPL sequences: template<typename T> struct pair_with:boost::mpl::pair{}; template struct sequence_product: boost::mpl::fold< Sequence1, boost::mpl::vector0<>, boost::mpl::joint_view< boost::mpl::_1, boost::mpl::transform< Sequence2, pair_withboost::mpl::_2 > >

{}; The file attached also exercises a possible implementation. Things are a little more complex now, I strongly suspect this kind of stuff can be more easily done with fusion, but alas I haven't had time to learn about that lib. Joaquín M López Muñoz Telefónica, Investigación y Desarrollo