[boost] [proto] docs: Calc2 improvement proposal

From: Markus Werle (numerical.simulation_at_[hidden])
Date: 2008-03-15 07:34:55

Hi!

First of all: This is a very nice example. 
Fantastic idea to introduce index information stored
in the terminals at this place in the docs - perfect.

If you define arg as 

template<int I> struct arg {};

and change the code accordingly the reader is not in need 
to know anything about mpl::int_ and IMHO the code

  template <int I>
  double operator ()(proto::tag::terminal, arg<I>) const
  {
    return d[ I - 1 ];
  }  

is easier to read than

  template<typename I>
  double operator ()(proto::tag::terminal, arg<I>) const
  {
     return d[ I() - 1 ];
  }
  

Note that this should be written for beginners like me, so
one catches the idea immediately without taking the extra path 
to mpl here.

Markus