[Boost-users] [MPL] at<> function with too many arguments

Subject: [Boost-users] [MPL] at<> function with too many arguments
From: Ryan McConnehey (mccorywork_at_[hidden])
Date: 2009-08-31 22:47:33

I have a mpl::map as follows, with a template parameter of a passed in 
type and a template parameter of "supported_type" that is a class.

using boost::mpl;
enum { value = 1 + supported_type::value };
typedef typename insert<typename supported_type::type_map, pair<T, 
int_<value> > >::type  type_map;

I'm trying to create a function that searches the map for a given type 
and returns a numeric value if it's found or -1 if it's not found.

template <typename S>  int typeValue(void)  {
  return at< type_map, S, int_<-1> >::type::value;
}

The documentation says I can specify a default value for "at" that is 
returned if the given key isn't found.  The compiler, though, says that 
I've provided too many arguments.  Have I called "at" incorrectly?  Is 
the documentation incorrect?  Is the fault with the compiler (VS 2005)?

Ryan