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From: steve@umigw.MIAMI.EDU (steve emmerson)
Newsgroups: comp.lang.c
Subject: Re: swaps with arrays
Message-ID: <110@umigw.MIAMI.EDU>
Date: Tue, 8-Sep-87 09:46:03 EDT
Article-I.D.: umigw.110
Posted: Tue Sep  8 09:46:03 1987
Date-Received: Wed, 9-Sep-87 03:54:53 EDT
References: <2376@zeus.TEK.COM>
Reply-To: steve@umigw.UUCP (steve emmerson)
Organization: University of Miami
Lines: 41
Summary: the key concept is "generic"

In article <1354@dataio.Data-IO.COM> bright@dataio.Data-IO.COM (Walter
Bright) wrote:
+--------
| Having a typeof would make creation of 'generic' routines possible:
|	#define swap(a,b)	{ typeof(a) tmp; tmp = a; a = b; b = tmp; }
+--------

To which I responded in article "<109@umigw.MIAMI.EDU> steve@umigw.UUCP"
saying:
+--------
|[swap macro] also won't work with pure array objects (i.e. swapping one
|array with another).  A generic routine should be able to work with
|*anything*.
+--------

Causing Dan Tilque to wonder [bear with me ;-)] (in article
<2376@zeus.TEK.COM> dant@tekla.UUCP):
+--------
|Can someone tell me why every one expects (or requires) a swap macro to 
|work with arrays?  The reason that they don't is that an array name is
|a constant and not an object.  ...
+--------

Well, I can't speak for everyone ;-), but if I was given a generic swap
routine that only worked on a subset of all possible data types ...
well, I might consider it very useful, but I wouldn't consider it
generic.  Someone please correct me if I'm wrong, but I believe a
"generic" routine is one that will work for any type of input (with a
caveat for the above example that the two arguments have the same
type).  Now, in the original article, Walter Bright had the word
"generic" in quotes.  Perhaps he was thinking along these lines and
ment to imply a "pseudo" or "quasi" generic routine (Walter?).

It might be best to chock the whole thing up to "zealous semantic
defense".  If the meaning of the word "generic" gets degraded, then
what word will we use?
-- 
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Steve Emmerson                     DDN: emmerson@miami.miami.edu
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