struct Report {
    template< typename Rep, typename T >
    static std::shared_ptr< Report > get( T t ) {
        return _get< Rep >( wibble::Preferred(), t );
    }

    template< typename Rep, typename T >
    static auto _get( wibble::Preferred, T t ) ->
        decltype( Rep::get( t ) )
    { return Rep::get( t ); }

    template< typename Rep, typename T >
    static auto _get( wibble::NotPreferred, T t )
        -> std::shared_ptr< Report >
    { return std::make_shared< Rep >( t ); }
};

struct SqlReport : Report {
#ifndef O_SQL_REPORT
    template< typename X >
    static std::shared_ptr< Report > get( X )
    { return nullptr; }
#endif
};