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=-1.9 required=5.0 tests=BAYES_00 autolearn=ham autolearn_force=no version=3.4.4 X-Google-Thread: 103376,21960280f1d61e84 X-Google-Attributes: gid103376,public X-Google-Language: ENGLISH,ASCII-7-bit Newsgroups: comp.lang.ada Subject: Re: in defense of GC References: <1169531612.200010.153120@38g2000cwa.googlegroups.com> <1mahvxskejxe1$.tx7bjdqyo2oj$.dlg@40tude.net> <2tfy9vgph3.fsf@hod.lan.m-e-leypold.de> <1g7m33bys8v4p.6p9cpsh3k031$.dlg@40tude.net> <14hm72xd3b0bq$.axktv523vay8$.dlg@40tude.net> <4zwt33xm4b.fsf@hod.lan.m-e-leypold.de> <1j7neot6h1udi$.14vp2aos6z9l8.dlg@40tude.net> <1pzx3y7d2pide.y744copm0ejb$.dlg@40tude.net> From: Markus E Leypold Organization: N/A Date: Tue, 06 Feb 2007 02:07:50 +0100 Message-ID: User-Agent: Some cool user agent (SCUG) Cancel-Lock: sha1:iCKal5X3XoP+FX3ROybAX05tlt8= MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii NNTP-Posting-Host: 88.74.38.71 X-Trace: news.arcor-ip.de 1170723766 88.74.38.71 (6 Feb 2007 02:02:46 +0200) X-Complaints-To: abuse@arcor-ip.de Path: g2news2.google.com!news3.google.com!border1.nntp.dca.giganews.com!nntp.giganews.com!newsfeed00.sul.t-online.de!newsfeed01.sul.t-online.de!t-online.de!newsfeed.arcor-ip.de!news.arcor-ip.de!not-for-mail Xref: g2news2.google.com comp.lang.ada:9006 Date: 2007-02-06T02:07:50+01:00 List-Id: Robert A Duff writes: > Ray Blaak writes: > >> Robert A Duff writes: >>> But in the latter, case, the return of Stepper is causing the lifetime >>> of an integer VARIABLE (i.e. mutable) to be longer than one might >>> suspect for a local variable of Make_A_Stepper. That seems like a >>> problem to me. >> >> Yes, the lifetime is longer (as specified by the programmer) but the global >> visibility is not affected -- N still cannot be directly manipulated in a >> global sense. > > My complaint is that it's not specified by the programmer on the > declaration of that variable (mutable object). Some nested procedure > happens to mention N and that procedure gets returned to a more-global > place, dragging N along with it. (Yes of course I understand that > "N still cannot be directly manipulated in a global sense.") But exactly the same happens with record fields. They are also mutable (when a record is returned). Why is it a problem here and not there? Regards -- Markus > > I've got no problem with passing functions (closures) outward in a > functional (no mutable variables) context. > > - Bob