Hi,

   I have read the section on Expression templates from Vandevoorde
and Josuttis, and I have coded a lighter version of the expression
template example, and it works quite well.
   In the assignment operator :

   template <typename T2, typename Rep2>
   Array & operator = ( Array<T2, Rep2> const & b )
   {

        for ( int idx = 0; idx < b.size ; ++idx )
            expr_rep[idx] = b[idx] ;

   }

  Note that the same index "idx" is passed on to all the nested
objects..  So if I have an expression like  x*y + x, then the
assignment operation would see x[i]*y[i] + x[i]. Agreed..
  What if i need different indices for each of the operation, like:

  x[i]*y[i+1] + x[i-1];

 Lets assume that the for loop doesn't span the full data range, so as
to accommodate the i-1 and i+1 index... Is there a way to expand
b[idx] such that I can pinpoint the operands individually ?

-dominic





-- 
      [ See http://www.gotw.ca/resources/clcm.htm for info about ]
      [ comp.lang.c++.moderated.    First time posters: Do this! ]