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Path: utzoo!yetti!geac!daveb
From: daveb@geac.UUCP
Newsgroups: comp.lang.c
Subject: Re: ANS C Macro Processing
Message-ID: <1687@geac.UUCP>
Date: Mon, 26-Oct-87 09:41:02 EST
Article-I.D.: geac.1687
Posted: Mon Oct 26 09:41:02 1987
Date-Received: Tue, 27-Oct-87 06:57:55 EST
References: <167@sdti.UUCP> <11323@orchid.waterloo.edu>
Reply-To: daveb@geac.UUCP (Dave Collier-Brown)
Organization: The little blue rock next to that twinkly star.
Lines: 25
Keywords: cpp
Summary: Intentions!

In article <11323@orchid.waterloo.edu> datanguay@watbun.waterloo.edu (David Tanguay) writes:
>In article <167@sdti.UUCP> turner%sdti@harvard.harvard.edu (Prescott K. Turner, Jr.) writes:
>}in the context of       #define z +y
>}                        #define y(b) z
>}                        #define f(a) f(a(3))


  I suspect the reason the ANSI committee came out with the
"rescanning turned off" was history:
  The C pre-processor was and is an improper subset of m4, the
Unix[tm] general-purpose preprocessor.  CPP was small and simple,
had a processing cost comparable to "cat" and didn't try to do
everything. M4 was more expensive and did more, and one used it when
one needed more, especially a quoting mechanism to control
rescanning.

  If the semantics of the current cpp can be achieved without
rescanning of X within expansion of X, then they may well be trying
for simplicity and compatibility...

-- 
 David Collier-Brown.                 {mnetor|yetti|utgpu}!geac!daveb
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