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From: lsr@apple.UUCP (Larry Rosenstein)
Newsgroups: comp.sys.mac
Subject: Re: Object Pascal
Message-ID: <398@apple.UUCP>
Date: Thu, 22-Jan-87 15:53:53 EST
Article-I.D.: apple.398
Posted: Thu Jan 22 15:53:53 1987
Date-Received: Fri, 23-Jan-87 06:46:47 EST
References: <4629@mit-eddie.MIT.EDU>
Reply-To: lsr@apple.UUCP (Larry Rosenstein)
Organization: Advanced Technology Group, Apple Computer
Lines: 50

In article <4629@mit-eddie.MIT.EDU> djd@eddie.MIT.EDU (Dave D'Souza writes:
>
>I am interested in receiving a little more information about MPW
>Pascal.  I know it is an object oriented language but I read somewhere
>(perhaps in this or the o-o languages newsgroup) that Object Pascal
>doesn't allow class definitions.  I am curious as to how one creates
>object and methods in this language.  Is is somewhat like lisp's
>flavors?
>

Object Pascal does not support class objects or class methods, but does
allow you to define new classes (object types).  For example, you can define
a general Shape object type that specifies a certain interface and then
define subclasses of Shape for Rectangle, Circle, etc.

It is possible to write code that sends messages to Shape objects without
knowing if they are in fact Rectangles, Circles, etc.  It is easy to create
a new subclass of shape and install it into your program.

For more information on Object Pascal you can look up Kurt Schmucker's book
"Object-Oriented Programming on the Macintosh" (published by Hayden).  There
have been articles in the August 1986 BYTE, the November & December 1986
MacWorld, and the Decemer 1986 MacTutor.  

Most of these articles talk about MacApp as well as Object Pascal.  MacApp
is an application framework written in Object Pascal that uses the
object-oriented extensions.  MacApp defines several object types (View,
Document, Command), which the programmer subclasses.  Your application
inherits the common Macintosh user interface (windows, menus, DAs, etc.)
from MacApp.

>Source code to a simple example program (it doesn't have to compile)
>would be much appreciated.  I just want to know if it is worth

The December MacTutor article that I wrote contained the source code for a
simple game program on the Macintosh.  That should give you an idea of what
Object Pascal is like.  




-- 
Larry Rosenstein

Object Specialist
Apple Computer

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