Re: template template parameters not working with STL containers

on Wed Feb 18 2009, vl106 <vl106-AT-hotmail.com> wrote:


<snip>

Others have explained the problem; I can offer some alternative
solutions:

1. Metafunction Class:

   // Create one of these for each container type
   struct make_deque
   {
       template <class T>
       struct apply
       {
           typedef std::deque<T> type;
       };
   };

   template <typename T, typename GenCont = make_deque>
   class Stack {
   private:
        typename GenCont<T>::type elems; // elements
      public:
        void push(T const&); // push element
   };

2. MPL Lambda Expression:

   #include <boost/mpl/apply.hpp>
   #include <boost/mpl/placeholders.hpp>
   namespace mpl = boost::mpl;

   template <typename T, typename GenCont = std::deque<mpl::_> >
   class Stack {
   private:
        typename mpl::apply<GenCont,T>::type elems;
      public:
        void push(T const&);
   };

See http://www.boost.org/libs/mpl and http://www.boostpro.com/mplbook
for more info.

Regards,

--
Dave Abrahams
BoostPro Computing
http://www.boostpro.com

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