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=-1.3 required=5.0 tests=BAYES_00,INVALID_MSGID autolearn=no autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 103376,5653f0bd43045b85 X-Google-Attributes: gid103376,public From: "Matthew Heaney" Subject: Re: garbage collection Date: 1999/08/21 Message-ID: <37becd7c@news1.us.ibm.net>#1/1 X-Deja-AN: 515520546 Content-transfer-encoding: 7bit References: <37be0c85@news1.us.ibm.net> <7pmad9$jnq$1@nnrp1.deja.com> X-Trace: 21 Aug 1999 16:02:04 GMT, 129.37.213.200 Organization: Global Network Services - Remote Access Mail & News Services X-Notice: should be reported to postmaster@ibm.net Content-Type: text/plain; charset="US-ASCII" Mime-version: 1.0 Newsgroups: comp.lang.ada X-Complaints-To: postmaster@ibm.net Date: 1999-08-21T00:00:00+00:00 List-Id: In article <7pmad9$jnq$1@nnrp1.deja.com> , Robert Dewar wrote: >>> It would be swell if the language were amended to make access types limited; >>> this would prevent any problems engendered by accidental copying of access >>> objects. > > There has *got* to be a smiley missing here. It is inconceivable > to make this change to the language (all access types limited) > and would be HIGHLY undesirable. Oh dear, I seemed to have confused people. No, I certainly don't mean make *all* access types limited. Only those access types specifically marked as limited, a la limited record types. > Presumably, if the above is not a joke (which it might be, > I am not sure), it is a proposal for some kind of extension > involving limited access types. Yes, it is a proposal for an extension involving limited access types. > Actually I think the reasonable thing to do is to extend the > storage pool abstraction so that a version of it contains > a copy operation that is called for all implicit copies of > the given access value. You probably want to introduce some > general controlled notion here. That would be really slick: being able to make access types controlled directly, instead of having to wrap the access object in a some kind of controlled abstraction (what I usually call a "handle"). -- Matt It is impossible to feel great confidence in a negative theory which has always rested its main support on the weak points of its opponent. Joseph Needham, "A Mechanistic Criticism of Vitalism"