Policy for Error genration.

Hi

Did anyone think about creation of the policy classes for genrating
Errors?

Generally there are in C++ 3 methods:

1. Old from C.
return "value of the error".

2. assert() or //or boost assertions

3. exceptions

Below is my proposition of the code for that purpose, but in my opinion
should be better solution for it, because there is too much copy of the
code in it.

foo < typename Condition_type, typename Error_policy >
{};

// class belo should be changed in macro with parameter "text"
template <
typename first_type,
typename second_type,
typename Binary_operation

struct Condition
{
         /* macro is important here
          */
         std::string text = "My condition";
         std::string what()
         {
                 return ( (text + "is not fulfill.") );
         };

         bool operator( first_type lhs, second_type rhs)
         {
                 return ( Binary_operation ( lhs, rhs ) );
         }
};

struct None_error_policy {};
struct Old_C_error_policy {};
struct Assert_policy {};
struct Exception_policy<typename Exception_type>
{ typedef Exception_type exception_type };

template< typename Condition_type >
struct foo < Condition_type, None_error_policy >
{
         int operator() throw()
         {}
};

template< typename Condition_type >
struct foo < Condition_type, Old_C_error_policy >
{
         int operator() throw()
         {
                 if ( Condition_type ( x, y ) )
                 {
                         return 1;
                 }
                 else
                 {
                         return 0;
                 }
         }
};

template< typename Condition_type >
struct foo < Condition_type, Assert_policy >
{
         int operator() throw()
         {
                 assert ( Condition_type ( x, y ) );
                 return 0;
         }
};

template< typename Condition_type >
struct foo < Condition_type, Exception_policy >
{
         int operator() throw ( typename
Exception_policy::exception_type )
         {
                 if ( Condition_type(x,y) )
                 {
                         throw typename Exception_policy::exception_type
(
                                         Condition_type.what()
                                 );
                 }
                 return 0;
         }
};

Best regards.

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