newbie Question about the macro BOOST_JOIN

From: zhangwusheng (yg-boost-users_at_[hidden])
Date: 2002-09-27 00:23:10

Hi,all,
In file suffix.hpp there are lines:

#define BOOST_JOIN( X, Y ) BOOST_DO_JOIN( X, Y )
#define BOOST_DO_JOIN( X, Y ) BOOST_DO_JOIN2(X,Y)
#define BOOST_DO_JOIN2( X, Y ) X##Y

why donot we define such macro instead:
#define BOOST_JOIN( X, Y ) X##Y

thanks in advance.