From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-2.9 required=5.0 tests=BAYES_00,MAILING_LIST_MULTI autolearn=unavailable autolearn_force=no version=3.4.4 X-Google-Thread: 103376,ec2a500cce3658c4 X-Google-Attributes: gid103376,public X-Google-Language: ENGLISH,ASCII-7-bit Path: g2news1.google.com!news2.google.com!news1.google.com!newsfeed.stanford.edu!nntp.cs.ubc.ca!freenix!enst.fr!melchior!cuivre.fr.eu.org!melchior.frmug.org!not-for-mail From: Stephen Leake Newsgroups: comp.lang.ada Subject: Re: Memory leak - What the ...? Date: 12 Oct 2004 20:14:09 -0400 Organization: Cuivre, Argent, Or Message-ID: References: <416C00D6.90402@netcabo.pt> NNTP-Posting-Host: lovelace.ada-france.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Trace: melchior.cuivre.fr.eu.org 1097626463 17743 212.85.156.195 (13 Oct 2004 00:14:23 GMT) X-Complaints-To: usenet@melchior.cuivre.fr.eu.org NNTP-Posting-Date: Wed, 13 Oct 2004 00:14:23 +0000 (UTC) To: comp.lang.ada@ada-france.org Return-Path: In-Reply-To: <416C00D6.90402@netcabo.pt> User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.3 X-Virus-Scanned: by amavisd-new-20030616-p10 (Debian) at ada-france.org X-BeenThere: comp.lang.ada@ada-france.org X-Mailman-Version: 2.1.4 Precedence: list List-Id: "Gateway to the comp.lang.ada Usenet newsgroup" List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Xref: g2news1.google.com comp.lang.ada:5114 Date: 2004-10-12T20:14:09-04:00 Marius Amado Alves writes: > >>I still lack an understandable explanation of why this does not leak: > >> > >> if This.Data /= null then > >> This.Data := new Stream_Element_Array'(This.Data.all); > >> end if; > > Adjust is called just after the members of the record have been > > copied. So imagine you have > > A := B; > > When Adjust(A) gets called, you will have > > A.Data = B.Data > > Since Data is an access type, you have a shallow copy where both A > > and > > B have members pointing to the same heap space. > > In the Adjust, what A does is replicate the pointed data to get a new > > pointer and a deep copy where A and B point to different heap copies. > > Additionally, before A being overwritten, Finalize(A) is called just > > in case it needs to free some memory. > > Hope this helps. > > Not really. The only way for leaking not to take place is for the old > This.Data value being held somewhere. Where? In B. Eventually, Finalize (B) is called. -- -- Stephe