Path: utzoo!attcan!uunet!cs.utexas.edu!usc!ucsd!ames!ads.com!sparkyfs!mckenney
From: mckenney@sparkyfs.istc.sri.com (Paul Mckenney)
Newsgroups: comp.lang.c++
Subject: Re: f***ing comments -- another pitfall to avoid
Message-ID: <31891@sparkyfs.istc.sri.com>
Date: 25 May 90 17:04:28 GMT
References: <1504@trlluna.trl.oz> <69.UUL1.3#5109@pantor.UUCP> <54683@microsoft.UUCP> <0682@sheol.UUCP> <54781@microsoft.UUCP>
Reply-To: mckenney@.itstd.sri.com (Paul E. McKenney)
Organization: SRI International, Menlo Park, CA 94025
Lines: 42

Even if you have a preprocessor that knows about C++ comments, one must
be careful...

Consider the following:
------------------------------------------------------------------------
	#define commentmacro \
			This is // (we interrupt this macro with a comment) \
			a test


	commentmacro
------------------------------------------------------------------------
Doing ``g++ -E'' yields:
------------------------------------------------------------------------
	# 1 "commentmacro.cc"
	 

				a test


	This is 
------------------------------------------------------------------------
Here, the ``//'' has apparently eaten the backslash, thus prematurely
terminating the comment.  I would prefer to see the ``//'' comment operate
up to (but not including) the next newline or the next backslash that is
immediately followed by a newline (whichever comes first).  This would yield
the more intuitive result:
------------------------------------------------------------------------
# 1 "commentmacro1.cc"
 




This is a test
------------------------------------------------------------------------

I guess that the moral of this story is that one should always use the
``/**/'' style comments inside of macro definitions, at least until the
``//'' comments behave more intuitively in mainstream implementations...

				Thanx, Paul