[Boost-users] [mpl] defaults with associative sequence

Subject: [Boost-users] [mpl] defaults with associative sequence
From: Manfred Doudar (manfred.doudar_at_[hidden])
Date: 2010-03-05 04:31:11

Hi,

Maybe I am misreading the documentation, but if I have an mpl::map and
try and get an element associated with a key all's good, while if I
assign a default - I get an error that mpl::at only takes 2 and
not 3 template parameters.

Simple example for sake of completness:

  using namespace boost::mpl;

  typedef map< pair<int, int_<0> >
             , pair<float, int_<1> >
             > m;

  at<m, float>::type::value;  // Ok

  at<m, double, int_<2> >::type::value;  // compiler error

Indeed a look in boost/mpl/at.hpp even leads me to believe that mpl::at
only takes two template parameters (maybe I mistaken), but documentation
suggests otherwise.

[Compiler:  GCC-4.4.2 ; Boost-1.42]

Am I doing something blatantly wrong?

Cheers,
-- 
Manfred