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: 103376,9a7e0c43216f4def X-Google-Attributes: gid103376,public From: "Pat Rogers" Subject: Re: "out" or "access" Date: 1998/10/22 Message-ID: <70nhch$nhr$1@supernews.com>#1/1 X-Deja-AN: 403940585 References: <908956499.754394@dedale.pandemonium.fr> <362DF0D3.BC101364@spam.innocon.com> <70kvnv$gvo$1@supernews.com> <70l1nq$mrb$1@cnn.Princeton.EDU> X-MimeOLE: Produced By Microsoft MimeOLE V4.72.2106.4 X-Complaints-To: newsabuse@supernews.com X-Trace: 909068497 Y6JRGRJUHDED2C640C usenet87.supernews.com Organization: http://www.supernews.com, The World's Usenet: Discussions Start Here Newsgroups: comp.lang.ada Date: 1998-10-22T00:00:00+00:00 List-Id: Martin C. Carlisle wrote in message <70l1nq$mrb$1@cnn.Princeton.EDU>... >Be careful using access as below, as this creates two different >dispatched objects in the call (which is illegal). See LRM 6.1(24) >and 3.9.2 You seem to be saying that there is no legal call with this approach, but neither RM reference supports that conclusion. The actual parameters to a call make a given call illegal or not, and that depends upon what is passed, per call. For example, if the actuals are statically-tagged -- the typical case -- there is no problem. If both actuals are dynamically-tagged they have to have the same tag, which is checked at run-time per RM 3.9.2(16). A call cannot have both statically-tagged and dynamically-tagged controlling operands, per RM 3.9.(8), but that is just one case. >> type T1 is tagged ... >> >> type T1_Pointer is access T1; >> >> procedure Foo( This : in T1; That : in T1_Pointer ); >> >>Then, in a derivation: >> >> type T2 is new T1 with ... >> >>This gives us: >> >> >> procedure Foo( This : in T2; That : in T1_Pointer ); >> >>Note that the type of the formal 'That' is still T1_Pointer, >>probably not what we wanted. >> >>On the other hand, had we defined things as: >> >> type T1 is tagged ... >> >> -- don't need this now... type T1_Pointer is access T1; >> >> procedure Foo( This : in T1; That : access T1 ); >> >>The derivation would provide >> >> procedure Foo( This : in T2; That : access T2 ); >> >>which is probably the desired result in this case. --- Pat Rogers Training & Development in: http://www.classwide.com Deadline Schedulability Analysis progers@acm.org Software Fault Tolerance (281)648-3165 Real-Time/OO Languages