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From: rlk@rational.com (Bob Kitzberger)
Newsgroups: comp.lang.ada,comp.lang.c++
Subject: Re: ADA Objects Help!
Followup-To: comp.lang.ada,comp.lang.c++
Date: 25 Jan 1995 18:18:09 GMT
Organization: Rational Software Corporation
Message-ID: <3g64l1$e7u@rational.rational.com>
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Xref: nntp.gmd.de comp.lang.ada:18308 comp.lang.c++:88050
Date: 1995-01-25T18:18:09+00:00
List-Id: <comp.lang.ada>

swdecato@nps.navy.mil wrote:

: In Ada the same program would be:
:
: 		Run(objectPtr);
: 		Sleep(objectPtr);
: 		Move(objectPtr);
: 		Set(objectPtr, A, B);

May I suggest an idiom that works better?  First, rid yourself of the
concept of "pointers" and "structs" when dealing with object-based Ada.
This may matter in the class implementation (package body), but clients
should be oblivious.

Second, name the package after the class you are modeling.  The package
package should export a type of that class (around here we just use
the identifier "Object", and often add some sort of "Object_Collection" type
if we want to export a list/set/map/whatever without having to create
a new package)

Third, use fully qualified names:

        My_Mower : Lawnmower.Object := Lawnmower.Create( Lawnmower.Toro );
        begin
            Robot_Arm.Run( My_Mower );
	    Robot_Arm.Sleep( My_Mower );
            Robot_Arm.Move( My_Mower );
            Robot_Arm.Destroy( My_Mower );
        end;


If Lawnmower.Object is dynamically allocated, then that is hidden in
in Create and Destroy (this is Ada83...)

One trap in learning a new language is to try to apply old idioms to the
new language; asking around on Usenet is a great way to find idioms
specific to the language.

	.Bob.

--
Bob Kitzberger	        +1 (916) 274-3075	        rlk@rational.com
Rational Software Corp., 10565 Brunswick Rd. #11, Grass Valley, CA 95945
     "Though the boys throw stones at frogs in sport, yet the frogs 
       do not die in sport but in earnest."      - Plutarch