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: 103376,901038687c38f61c X-Google-Attributes: gid103376,public X-Google-Language: ENGLISH,ASCII-7-bit Path: g2news1.google.com!news1.google.com!newshub.sdsu.edu!elnk-nf2-pas!newsfeed.earthlink.net!stamper.news.pas.earthlink.net!newsread3.news.pas.earthlink.net.POSTED!a6202946!not-for-mail From: Jeffrey Carter Organization: jrcarter commercial-at acm [period | full stop] org User-Agent: Mozilla/5.0 (Windows; U; Win98; en-US; rv:1.4) Gecko/20030624 X-Accept-Language: en-us, en MIME-Version: 1.0 Newsgroups: comp.lang.ada Subject: Re: Idiom for a class and an object in Ada References: In-Reply-To: Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Message-ID: Date: Thu, 21 Oct 2004 01:36:28 GMT NNTP-Posting-Host: 63.184.104.254 X-Complaints-To: abuse@earthlink.net X-Trace: newsread3.news.pas.earthlink.net 1098322588 63.184.104.254 (Wed, 20 Oct 2004 18:36:28 PDT) NNTP-Posting-Date: Wed, 20 Oct 2004 18:36:28 PDT Xref: g2news1.google.com comp.lang.ada:5554 Date: 2004-10-21T01:36:28+00:00 List-Id: Matthew Heaney wrote: > For reasons I can't fathom, many Ada95 developers still have a very > Ada83 mindset. That's because Ada 83 was a very good language, and the idioms that were good for it are still good. > This is the canonical idiom in C++ for controlling instance creation: > > class C { > public: > > static C* make( /* ... */ ); > static void free(C*); > > void f(); //whatever > > private: > > C(); > C(const C&); > > ~C(); > > C& operator=(const C&); > }; > > Here, the ctor (and dtor) is declared as private, so the only way to > make a C object is by calling factory function C::make(). > > This has a direct translation into Ada95: > > package P is > > type T (<>) is limited private; > > procedure Op (O : in out T); > > type T_Access is access all T; > > function New_T (...) return T_Access; And this is why C++ is never a good guide to how to do things in Ada. The pointer may well be needed in C++; it's not needed in Ada. -- Jeff Carter "Ada has made you lazy and careless. You can write programs in C that are just as safe by the simple application of super-human diligence." E. Robert Tisdale 72