Re: [Boost-users] [mpl] cross product of 2 sequences

on Wed Nov 21 2007, Roman Perepelitsa wrote:

I need metafunction cross_product, which should transform 2 sequences to a sequence of pairs.

Example:

typedef list l1; typedef list l2; typedef cross_product::type c; typedef list< pair, pair, pair, pair

...

e; BOOST_MPL_ASSERT((equal));

The best definition I came up with is the following:

template struct product : transform > { };

template struct cross_product : fold< typename transform >::type, list<>, joint_view<_1, _2> > { };

Is there a better way to do it?

Depends what your criteria for "better-ness" are.

How can I get rid of 'struct product' and implement it as one metafunction?

If you're just trying to minimize the amount of code, the above is pretty good. -- Dave Abrahams Boost Consulting http://www.boost-consulting.com