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,FREEMAIL_FROM, INVALID_MSGID autolearn=no autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII X-Google-Thread: 103376,b14a804025dceb20 X-Google-Attributes: gid103376,public From: Francois Godme Subject: Re: Constructors/Destructors in Ada95 Date: 2000/10/22 Message-ID: <39F36CAA.94B9702C@bigfoot.com>#1/1 X-Deja-AN: 684585686 Content-Transfer-Encoding: 8bit References: <39EE160D.F0A2000@bigfoot.com> <39EF5431.BF4CD793@bigfoot.com> <8svc01$c75$1@nnrp1.deja.com> X-Accept-Language: fr, en-US, en Content-Type: text/plain; charset=iso-8859-1 X-Complaints-To: abuse@proxad.net X-Trace: nnrp5.proxad.net 972254230 212.27.44.139 (Mon, 23 Oct 2000 00:37:10 CEST) Organization: Guest of ProXad - France MIME-Version: 1.0 NNTP-Posting-Date: Mon, 23 Oct 2000 00:37:10 CEST Newsgroups: comp.lang.ada Date: 2000-10-22T00:00:00+00:00 List-Id: rwilson007007@my-deja.com a �crit : > in order to achieve the same effect as constructor arguments in c++ it > is helpful to define an attributes class for each application-object > class (with the same inheritance pattern as the application classes). > the attributes class tagged record contains a field for each application > -class tagged record field requiring explicit initialization. > > then, define the base class tagged record for your > application-object classes with a classwide access value to a > constant attributes class instance as one of its members. > > finally, the base class constructor reads the initial-attributes values > for its attributes member from config files (for example). the > inheriting classes then look-up the appropriate initial values in > This.Attributes (for "Initialize (This : in out access Object)").... > > another way is to is enclose your classes in generic packages with the > generic formal parameters corresponding to constructor arguments. > however, this would seem to force a singleton pattern. To rwilson, I will say that I am not sure that I fully undestand its proposal. For instance, I am not sure how different instances get initialized with different values in these scheme. Also, I am not sure if it needs not twice the memory, once in the application classes and once in the initializing classes. Anyway, I admit that for exemple with a public access discriminant to a string in the base class, the Initialize procedures could lookup somewhere, somehow with this name for values to initialize the instance. I find it too difficult to handle and prefer Tucker Taft's direct manner with non-primitive functions returning initialized instances for non-limited types and non-primitive procedures for limited types. Marin David Condic has said: "Remember that Ada is not C++. You can pretty much get the same net effect of constructors and destructors in Ada - but not in exactly the same way. So you change the model instead. Since Ada doesn't treat assignment the same way as C++ and you don't have the same parameter features, you've got to work with what Ada does provide and try not to make it look exactly like C++. The job does get done and, IMHO, it is a lot less semantically messy when done in Ada as opposed to C++." To Marin David Condic, I will say, well, recently, the model has been changed to make it look more like C++ by adding the "with type" feature which was felt lacking after feature comparisons with Java and C++. Some people complained they couldn't get the work done with what Ada provides. I take C++ as an exemple because C++ got inspired a lot by Ada83 in my opinion. C++ has pragmas, inlined routines, generics (templates), public and private parts (as well as protected parts), parameter passing modes, default parameters, constant objects, operators and methods overloading, (poor) enumeration types, exceptions, renamings (you can think of C++ references as renamings of objects.). C++ has also well-thought constructors. No pun intended.