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: 103376,9d0b383ee17c13af X-Google-Attributes: gid103376,public From: Tucker Taft Subject: Re: One type for all Date: 1999/07/19 Message-ID: <3793449B.6622DA6D@averstar.com>#1/1 X-Deja-AN: 502747901 Content-Transfer-Encoding: 7bit Sender: news@inmet.camb.inmet.com (USENET news) X-Nntp-Posting-Host: houdini.burl.averstar.com References: <3783E0D2.5D74243@boeing.com> <3786741C.E73F1124@hso.link.com> <7mdobd$fu$1@nnrp1.deja.com> <1999Jul12.193436.1@eisner> <7mqueq$k7e$1@nnrp1.deja.com> <7mttci$edv$1@nnrp1.deja.com> Content-Type: text/plain; charset=us-ascii Organization: AverStar (formerly Intermetrics) Burlington, MA USA Mime-Version: 1.0 Newsgroups: comp.lang.ada Date: 1999-07-19T00:00:00+00:00 List-Id: Robert Dewar wrote: > ... > So thanks, it is indeed the case that Pascal does NOT have > structural type equivalence, which is what I remembered (any > other conclusion would have been a big surprise!) I suspect the confusion comes from the early Pascal reports (e.g. <= 2nd ed.), which were in fact ambiguous on the issue of type equivalence, leading some implementations to choose name equivalence, and others to choose structural equivalence. For structured assignment, it required the types to be "identical" but it didn't define that in any rigorous way. The ISO standard opted for name equivalence, but by that time, there were already implementations using structural equivalence. The initial ISO standard was weak enough that it might not have been sufficient to get all implementors to follow the official rules. -- -Tucker Taft stt@averstar.com http://www.averstar.com/~stt/ Technical Director, Distributed IT Solutions (www.averstar.com/tools) AverStar (formerly Intermetrics, Inc.) Burlington, MA USA