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From: sakkinen@jyu.fi (Markku Sakkinen)
Subject: Re: Zero-length structures and pointer comparisons
Message-ID: <1992Oct22.180951.24111@jyu.fi>
Organization: University of Jyvaskyla, Finland
References: <23915@alice.att.com> <1992Oct19.055511.18826@jyu.fi> <23937@alice.att.com>
Date: Thu, 22 Oct 1992 18:09:51 GMT
Lines: 44

In article <23937@alice.att.com> ark@alice.UUCP () writes:
>In article <1992Oct19.055511.18826@jyu.fi> sakkinen@jyu.fi (Markku Sakkinen) writes:
>
>> In article <23915@alice.att.com> ark@alice.UUCP () writes:
>
>> >For example, if a type T has a < operator defined that is actually a strong
>> >total order relation, that makes it possible to store T objects efficiently
>> >in a variety of order-based data structures such as M,N-trees, etc.
>
>> Sorry, there is a misunderstanding here.
>> The discussion in this thread (see subject line) has been about _pointer_
>> comparisons all the time.  Comparison of object values is another story
>> altogether.
>
>No misunderstanding.
>
>I made a general statement about potentially useful properties of arbitrary
>types.  That statement still holds true when those types happen to be pointer
>types.  That is, if < were defined as a strong total ordering on pointers,
>I could use these data structures to keep track of sets of pointers.

Thus, while Jim Adcock, in the posting to which you had originally replied,
was quite happy with the situation as is, you would be in favour of a change
in the standard to make pointer types totally ordered?

Above, you omitted exactly that part of your earlier posting
that was mixing things up (immediately following the first quote):

>> >There are many applications for such structures.  For example, one might make
>> >the constructor and destructor for class T use such a structure to keep
>> >track of all the T objects in the universe, and so on.

Pointer types are not classes, and they cannot have constructors or
destructors.

----------------------------------------------------------------------
Markku Sakkinen (sakkinen@jytko.jyu.fi)
       SAKKINEN@FINJYU.bitnet (alternative network address)
Department of Computer Science and Information Systems
University of Jyvaskyla (a's with umlauts)
PL 35
SF-40351 Jyvaskyla (umlauts again)
Finland
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