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List:       boost-users
Subject:    [Boost-users] =?utf-8?b?W3ZhcmlhbnRdLlthcHBseV92aXNpdG9yXSBCaW5h?=
From:       Prashant Thakre <prashant.thakre () gmail ! com>
Date:       2006-07-10 10:25:57
Message-ID: loom.20060710T115047-875 () post ! gmane ! org
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Hi,
 Compiler instantiates the second Binary visitor instead of the first one even 
though the template parameters are same.
regards,
Prashant

---------------------------------------------------------------------------
struct add_tuple_visitor: public boost::static_visitor<bool> {

  // Expected this to be instantiated by the compiler.
  // 1.
  template <typename T>
  bool operator()( T & lhs, const T & rhs) const
  {
    lhs += rhs ;
    return true;
  }

  // Compiler considers this as an appropriate fit ..
  // 2.
  template <typename T, typename U>
  bool operator()( T & lhs, const U & rhs) const
  {
    lhs += rhs ;
    return true;
  }

};

struct agg_calc {
 public:
   template <typename T>
   bool operator ()  ( 
		T & lhs,  
            const T & rhs
   ) const {
	 for(
	   std::size_t curr_oper = 0;
	   curr_oper < num_operations;
	   ++v
	 ) {
	   switch(
	     agg_operators.at(curr_oper)
	   ) {
	     case '+' :
		 boost::apply_visitor(
                          agg_visitor, 
                          lhs.at(curr_oper), //vector of variants
                          rhs.at(curr_oper) //vector of variants
                       );
		 break;

	     default:
		 break;
	    };

	 } // for loop 

	 return true;
   }
		
   //Store the aggregation operators
   agg_types agg_operators;
   std::size_t num_operations;

   // Create visitor objects for delayed form of apply_visitor
   add_tuple_visitor agg_visitor;
};
---------------------------------------------------------------------------


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