Path: utzoo!dciem!nrcaer!cognos!jimp
From: jimp@cognos.uucp (Jim Patterson)
Newsgroups: comp.lang.c
Subject: Re: Variable function names
Message-ID: <2006@cognos.UUCP>
Date: 28 Dec 87 05:21:50 GMT
Article-I.D.: cognos.2006
Posted: Mon Dec 28 00:21:50 1987
References: <973@russell.STANFORD.EDU> <47000025@uxe.cso.uiuc.edu>
Reply-To: jimp@cognos.UUCP (Jim Patterson)
Organization: Cognos Inc., Ottawa, Canada
Lines: 19

In article <47000025@uxe.cso.uiuc.edu> mcdonald@uxe.cso.uiuc.edu writes:
>I learned C with the explicit assumption that, since it allowed both
>data and function pointers, one could take an array, write a program that
>generated compiled code in that array, cast the address of (the first
>byte of) the array to a function pointer, and call that function. 
>     I have since learned that on some systems (i.e. 80286 Xenix in anything
>except single-segment model) it won't work, and that ANSI C does not
>require it to work (A FATAL FLAW).
This is hardly a FATAL FLAW, since it's an unusual application that would
depend on such an ability. It's also a stance that is consistent with
the ANSI C objective of standardizing a version of C that is widely
implementable. Executing code in data space is extremely difficult on
some architectures, for example the HP/3000 which has completely
segregated code and data spaces. 
-- 
Jim Patterson                              Cognos Incorporated
UUCP:decvax!utzoo!dciem!nrcaer!cognos!jimp P.O. BOX 9707    
PHONE:(613)738-1440                        3755 Riverside Drive
                                           Ottawa, Ont  K1G 3Z4