А>#define DEFINE_TRANSACTION(T, NAME, ARGT)    static T NAME(ARGT arg){ \
А>    int encript = 0; /* encript result or no. Always 0 */ \
А>    T    result; \
А>    . . .
А>}
А>

#include <boost/preprocessor/cat.hpp>

#define TRANSACTION_ENCRYPTION_TRANSACTION_ENCRYPTION 0,
#define TRANSACTION_ENCRYPTION_TRANSACTION_ENCRYPTION_TRANSACTION_ENCRYPT 1

#define TRANSACTION_ENCRYPTION(x) BOOST_PP_CAT(TRANSACTION_ENCRYPTION_, x),
#define TRANSACTION_ENCRYPTION_I(x) ( BOOST_PP_CAT(TRANSACTION_ENCRYPTION_, TRANSACTION_ENCRYPTION x) )


#define GET_TRANSACTION_ENCRYPTION_I(is_encrypt, ret_type) is_encrypt
#define GET_TRANSACTION_ENCRYPTION(x) GET_TRANSACTION_ENCRYPTION_I TRANSACTION_ENCRYPTION_I(x)

#define GET_TRANSACTION_RET_TYPE_I(is_encrypt, ret_type) ret_type
#define GET_TRANSACTION_RET_TYPE(x) GET_TRANSACTION_RET_TYPE_I TRANSACTION_ENCRYPTION_I(x)

#define ENCRYPT(x) (TRANSACTION_ENCRYPT) x

#define DEFINE_TRANSACTION(ret_type, name, arg_type) \
static GET_TRANSACTION_RET_TYPE(ret_type) name(arg_type arg) \
{ \
     int encrypt = GET_TRANSACTION_ENCRYTION(ret_type); \
     GET_TRANSACTION_RET_TYPE(ret_type) result; \
     return result; \
}