Xref: utzoo comp.object:528 comp.lang.c++:5709
Path: utzoo!utgpu!watserv1!watmath!watmsg!gjditchfield
From: gjditchfield@watmsg.waterloo.edu (Glen Ditchfield)
Newsgroups: comp.object,comp.lang.c++
Subject: Re: Dumb question
Message-ID: <32106@watmath.waterloo.edu>
Date: 29 Nov 89 16:24:27 GMT
References: <61737@aerospace.AERO.ORG> <9938@june.cs.washington.edu> <2122@tukki.jyu.fi> <2159@tukki.jyu.fi> <9191@microsoft.UUCP>
Sender: daemon@watmath.waterloo.edu
Reply-To: gjditchfield@watmsg.waterloo.edu (Glen Ditchfield)
Organization: U. of Waterloo, Ontario
Lines: 23

In article <9191@microsoft.UUCP> jimad@microsoft.UUCP (Jim Adcock) writes:
>// in any case -- here's a quick and dirty example of what I think 
>// people have been talking about....
[Code that sketches a sortable list omitted.]

Note that the list's sort() function used the `<' function defined by the
list element class, which in turn used a virtual compare() function.  I
think some people were talking about this, but other people wrote about a
scheme where the compare() function is a virtual function of the list
class.
   I like putting compare() in the list class better.  You can have
different lists that sort the same element type in different ways; invoices
sorted by customer in one list, and by date in another.  The sort routine
isn't bound to one element class function name, like `<'.  You can sort by
things like string length, which wouldn't normally be done with `<'.
   In practice, in C++, wouldn't it be simpler to pass a comparison
function as an argument to the sort() function?  If the list's elements are
always sorted in the same order, the list insertion operation would insert
elements in that order in the first place.

    Glen Ditchfield  gjditchfield@violet.uwaterloo.ca  Office: DC 2517
Dept. of Computer Science, U of Waterloo, Waterloo, Ontario, Canada, N2L 3G1
			 Gorbachev is a CIA mole.


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