Path: utzoo!utgpu!water!watmath!clyde!ima!haddock!karl
From: karl@haddock.ISC.COM (Karl Heuer)
Newsgroups: comp.lang.c
Subject: Re: Machine specific predefined names
Message-ID: <3297@haddock.ISC.COM>
Date: 2 Apr 88 02:26:08 GMT
References: <1988Feb17.115402.12739@light.uucp> <17033@watmath.waterloo.edu> <242@sdrc.UUCP> <378@wsccs.UUCP> <3225@haddock.ISC.COM> <598@tuvie> <3264@haddock.ISC.COM> <5202@sdcrdcf.UUCP>
Reply-To: karl@haddock.ima.isc.com (Karl Heuer)
Organization: Interactive Systems, Boston
Lines: 19

In article <5202@sdcrdcf.UUCP> markb@sdcrdcf.UUCP (Mark Biggar) writes:
>In article <3264@haddock.ISC.COM> karl@haddock.ima.isc.com (Karl Heuer) writes:
>>That isn't portable.  After you've redefined something, you have no way of
>>knowing whether other library routines (e.g. puts) will be using your
>>putchar or the standard one.
>
>I thought the standard included a guarantee that if you did the above that
>the libraries would still continue to use the original definition.
>In fact the whole reason for the necessity of using the #undef etc. was to
>allow for that guarantee.

No, it's guaranteed that the libraries will not depend on NON-standard
functions (e.g. you can safely use "open" without worrying that "fopen" calls
a function of that name), but the names of the standard routines are reserved.

(Note: "putchar" is a bad example, because it happens to work in the usual
implementation.  But "malloc" does not, and neither does "putc".)

Karl W. Z. Heuer (ima!haddock!karl or karl@haddock.isc.com), The Walking Lint