Re: [boost] [preprocessor] Patch for stringize.hpp

From: Steve Cornett (boost_at_[hidden])
Date: 2006-02-21 01:39:52

Thanks for the detailed answer.  I now see more of the overall purpose of 
the macros in stringize.hpp, but your 2nd example does not in fact require 
the ## operator to get the behavior you want with Microsoft C++.  If you 
delete the ## out of macro B, leaving everything else in place, there is no 
difference in the behavior; you still get p + q.  I tried this with 
Microsoft Visual C++ 5 (v11) and Microsoft Visual C++ 2005 (v14):

#define IM p, q
#define A(im) B((im))
#define B(par) C par    // no ## here
#define C(x, y) x + y
A(IM) // p + q

So despite your impressive knowledge of Microsoft's preprocessor bugs, I'm 
not really convinced the ## is needed in stringize.hpp, at least with 
Microsoft C++.

I see the similar ## usage in cat.hpp and iif.hpp, but that code seems 
limited to Metrowerks.  I'm really only interested in Microsoft C++.  In 
stringize.hpp was the only place ## was used to produce an invalid token 
when I built boost with Microsoft C++ ("bjam -sTOOLS=vc-8_0").  There may be 
others places, but those wheels didn't squeak for me.