Re: Destructors can copying objects

From	drew@furrfu.invalid (Drew Lawson)
Newsgroups	comp.lang.c++
Subject	Re: Destructors can copying objects
Date	2011-04-05 20:37 +0000
Organization	Center for Unverified Assertions
Message-ID	<infuie$2cmp$1@raid.furrfu.com> (permalink)
References	<in76i3$105$2@reader1.panix.com> <infdqj$hvf$2@reader1.panix.com> <infkik$28sd$1@raid.furrfu.com> <inftr3$hvf$3@reader1.panix.com>

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In article <inftr3$hvf$3@reader1.panix.com>
	Ruben Safir <ruben@mrbrklyn.com> writes:
>On Tue, 05 Apr 2011 17:47:00 +0000, Drew Lawson wrote:
>
>> It wouldn't matter if it did, in this case. a.ptr and b.ptr are two
>> different pointers.  If
>>   delete a.ptr;
>> cleared the pointer, it would have no way of knowing about b.ptr.
>
>when you do a delete, it doesn't seem to delete the pointer, but the memory
>at the address that the pointer is storing.  I could be wrong, but that
>is the basis of the double delete.
>...
>
>I see.  Your right.  is b.ptr is wiped to null, a.ptr is still pointing to 
>a dellocated part of the heap.  But if the pointers are passed by reference,
>a.ptr and b.ptr are actually the same pointer inside a single object.

I may have accidentally confused you.  (My phrasings aren't always
as clear as I believe they are.)

You are correct that delete frees the memory and does not clear the
pointer handed to it.

I was pointing out that in the case of a copied pointer, it wouldn't
help even if delete *did* clear the pointer because it couldn't
clear the other pointer in the other object.


-- 
Drew Lawson            | "Look!  A big distracting thing!"
                       |     -- Crow T. Robot.
                       |

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Thread

Destructors can copying objects Ruben Safir <ruben@mrbrklyn.com> - 2011-04-02 12:58 +0000
  Re: Destructors can copying objects Volker Lukas <vlukas@gmx.de> - 2011-04-02 15:29 +0200
    Re: Destructors can copying objects Ruben Safir <ruben@mrbrklyn.com> - 2011-04-03 02:59 +0000
      Re: Destructors can copying objects "Balog Pal" <pasa@lib.hu> - 2011-04-03 11:32 +0200
        Re: Destructors can copying objects Leigh Johnston <leigh@i42.co.uk> - 2011-04-03 12:29 +0100
          Re: Destructors can copying objects Bart van Ingen Schenau <bart@ingen.ddns.info> - 2011-04-04 13:43 +0200
            Re: Destructors can copying objects Michael Doubez <michael.doubez@free.fr> - 2011-04-05 01:26 -0700
          Re: Destructors can copying objects Joshua Maurice <joshuamaurice@gmail.com> - 2011-04-04 14:03 -0700
            Re: Destructors can copying objects Ruben Safir <ruben@mrbrklyn.com> - 2011-04-04 21:10 +0000
            Re: Destructors can copying objects Leigh Johnston <leigh@i42.co.uk> - 2011-04-04 22:28 +0100
          Re: Destructors can copying objects Ruben Safir <ruben@mrbrklyn.com> - 2011-04-04 21:07 +0000
            Re: Destructors can copying objects Leigh Johnston <leigh@i42.co.uk> - 2011-04-04 22:31 +0100
              Re: Destructors can copying objects Leigh Johnston <leigh@i42.co.uk> - 2011-04-04 22:43 +0100
              Re: Destructors can copying objects Ruben Safir <ruben@mrbrklyn.com> - 2011-04-04 22:38 +0000
                Re: Destructors can copying objects Leigh Johnston <leigh@i42.co.uk> - 2011-04-04 23:42 +0100
                Re: Destructors can copying objects Ruben Safir <ruben@mrbrklyn.com> - 2011-04-04 22:54 +0000
      Re: Destructors can copying objects James Kanze <james.kanze@gmail.com> - 2011-04-03 10:07 -0700
        Re: Destructors can copying objects Ruben Safir <ruben@mrbrklyn.com> - 2011-04-04 21:14 +0000
        Re: Destructors can copying objects Ruben Safir <ruben@mrbrklyn.com> - 2011-04-04 21:17 +0000
          Re: Destructors can copying objects LR <lruss@superlink.net> - 2011-04-05 01:52 -0400
    Re: Destructors can copying objects Ruben Safir <ruben@mrbrklyn.com> - 2011-04-03 03:08 +0000
      Re: Destructors can copying objects Paavo Helde <myfirstname@osa.pri.ee> - 2011-04-03 02:11 -0500
      Re: Destructors can copying objects Volker Lukas <vlukas@gmx.de> - 2011-04-03 12:02 +0200
      Re: Destructors can copying objects Peter Remmers <p.remmers@expires-2011-04-30.arcornews.de> - 2011-04-03 12:14 +0200
        Re: Destructors can copying objects Roberto Waltman <usenet@rwaltman.com> - 2011-04-03 18:16 -0400
          Re: Destructors can copying objects Ruben Safir <ruben@mrbrklyn.com> - 2011-04-15 23:06 +0000
            Re: Destructors can copying objects LR <lruss@superlink.net> - 2011-04-15 19:19 -0400
        Re: Destructors can copying objects Ruben Safir <ruben@mrbrklyn.com> - 2011-04-15 23:03 +0000
          Re: Destructors can copying objects "Alf P. Steinbach /Usenet" <alf.p.steinbach+usenet@gmail.com> - 2011-04-16 01:47 +0200
            Re: Destructors can copying objects Peter Remmers <p.remmers@expires-2011-04-30.arcornews.de> - 2011-04-16 13:00 +0200
              Re: Destructors can copying objects "Alf P. Steinbach /Usenet" <alf.p.steinbach+usenet@gmail.com> - 2011-04-16 15:57 +0200
  Re: Destructors can copying objects LR <lruss@superlink.net> - 2011-04-02 09:51 -0400
  Re: Destructors can copying objects Yannick Tremblay <yannick@tremnblay.co.uk> - 2011-04-04 12:56 +0000
    Re: Destructors can copying objects Ruben Safir <ruben@mrbrklyn.com> - 2011-04-04 21:05 +0000
      Re: Destructors can copying objects Paavo Helde <myfirstname@osa.pri.ee> - 2011-04-04 21:56 -0500
      Re: Destructors can copying objects Yannick Tremblay <yannick@tremnblay.co.uk> - 2011-04-05 11:36 +0000
        Re: Destructors can copying objects Ruben Safir <ruben@mrbrklyn.com> - 2011-04-05 15:40 +0000
          Re: Destructors can copying objects Sana <sanatakos@gmail.com> - 2011-04-05 10:11 -0700
          Re: Destructors can copying objects Ruben Safir <ruben@mrbrklyn.com> - 2011-04-05 20:28 +0000
          Re: Destructors can copying objects Yannick Tremblay <yannick@tremnblay.co.uk> - 2011-04-06 11:12 +0000
      Re: Destructors can copying objects drew@furrfu.invalid (Drew Lawson) - 2011-04-05 13:02 +0000
        Re: Destructors can copying objects Ruben Safir <ruben@mrbrklyn.com> - 2011-04-05 15:51 +0000
          Re: Destructors can copying objects drew@furrfu.invalid (Drew Lawson) - 2011-04-05 17:47 +0000
            Re: Destructors can copying objects Ruben Safir <ruben@mrbrklyn.com> - 2011-04-05 20:25 +0000
              Re: Destructors can copying objects drew@furrfu.invalid (Drew Lawson) - 2011-04-05 20:37 +0000

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