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From: ari@eleazar.dartmouth.edu (Ari Halberstadt)
Newsgroups: comp.lang.c
Subject: Re: problem with cc compiler
Message-ID: <14631@dartvax.Dartmouth.EDU>
Date: 25 Jul 89 04:05:33 GMT
References: <712@unsvax.NEVADA.EDU> <10589@smoke.BRL.MIL> <1185@fcs280s.ncifcrf.gov> <10594@smoke.BRL.MIL> <4935@alvin.mcnc.org> <10599@smoke.BRL.MIL>
Sender: news@dartvax.Dartmouth.EDU
Reply-To: ari@eleazar.dartmouth.edu (Ari Halberstadt)
Organization: Dartmouth College, Hanover, NH
Lines: 32

In article <10599@smoke.BRL.MIL> gwyn@brl.arpa (Doug Gwyn) writes:
>In article <4935@alvin.mcnc.org> spl@mcnc.org.UUCP (Steve Lamont) writes:
>>Suppose that I wish to implement my own math library function, say sin() or
>>cos(), for whatever reason, in a large pre-existing piece of code that I don't
>>want to fiddle too much with.  How would I do this, then?
>Much better would be for you to name your functions my_cos() and my_sin(),
>and include something like the following in your application header file:
>        #undef cos      /* in case <math.h> uses a #define cos $$COS etc. */
>        #define cos     my_cos
>        #undef sin
>        #define sin     my_sin

I must voice a small criticism of the above scheme. By redefining a standard
function name, you may be greatly confusing any programmers who try
to read your code. These programmers will expect 
any standard named function to be IDENTICAL to the standard library function.
Unless you've completely debugged and tested it for compatability, they
won't know what hit them.
Also, what if someone copies your code without including the header file,
since they assumed it was not needed. Then, when they try to run it,
it won't perform!
I think there was another reason, but I can't remember it right now.
At any rate, I always opt for calling functions either "my_sin()",
or "xsin()". I use the second when I'm sick of seeing "my" all over
the place (for instance, on the Macintosh I replaced the standard
file package with my own mini-package, and prefixed all the standard
names with "x", to get "xfopen()", xgetc() "XFILE *", "xstdio.h", etc.)
On UNIX you can use the tools "ed" or "sed" (or awk if you want to
be fancy...) to change all the original function calls.
-- Ari Halberstadt '91, "Long live succinct signatures"
E-mail: ari@eleazar.dartmouth.edu	Telephone: (603)640-5687
Mailing address: HB1128, Dartmouth College, Hanover NH 03755