Hi, Kevin and All
Your comment about using instance variables as 'pointers' raises an
interesting question of how object oriented programming has conceptually
replaced pointers. A transition from a pointer-intensive language like C,
where pointers are used compulsively even if they are not necessary, to an
object-oriented language such as C++, Delphi or more restrictively Java.
Where have all those pointers gone ? :-) and how do object-oriented
languages design-pattern them out of explicit code all together?
All the best,
Paule
----- Original Message -----
From: "kevin" <[EMAIL PROTECTED]>
To: "Borland's Delphi Discussion List" <[email protected]>
Sent: Monday, April 24, 2006 12:33 AM
Subject: Re: Delphi and Java
>
> ----- Original Message -----
> From: "Alan Colburn" <[EMAIL PROTECTED]>
> To: "Borland's Delphi Discussion List" <[email protected]>
> Sent: Friday, April 21, 2006 11:27 AM
> Subject: Re: Delphi and Java
>
>
>> The difficulties come when I try to apply the ideas to real world
>> situations. First, it seems like there's a lot of applications that are
>> simpler to write in a more procedural style, e.g., general utility or
>> office-like apps for individual users, like a text editor, mp3 player, or
>> file utility program.
>
>> Second, even when trying to create something that
>> *does* fit well (even to me) within an object oriented viewpoint, it's
> hard
>> for me to figure out where best to place methods, and how to have objects
>> communicate with one another. For example, if one were writing an
>> application related to managing students registering for courses, it
>> makes
>> sense to have Student objects and Course objects. When one registers,
>> though, these objects would need to communicate with each other. I would
>> have trouble deciding how to do that, while keeping classes/objects
>> "encapsulated," and deciding where to place a Register method--after all,
>> registration affects *both* the Student and the Course.
>
> One technique I often use in a custom class is to put a 'pointer' or
> instance variable to another custom class:
>
> eg.
> tCourse = class(tcomponent)
> public
> CourseName: string;
> //course specific variables/methods etc.
> end;
>
> tStudent = class(tcomponent)
> public
> Course : tcourse;
> procedure Register(CourseName: string);
> //student specific variables/methods etc.
> end;
>
> var Student: tStudent;
>
> The Register method in tStudent could be used to assign the value of
> CourseName
> which may then be referenced as Student.Course.CourseName
>
> An instance, Student, of tStudent has to create an instance of Course in
> its
> constructor
> (so that Course has assigned memory and is not NULL),
> but then all the methods of tCourse are already available within the
> tStudent
> object;
>
> It's possible to create hierarchies of components like this, each having
> other
> components nested internally;
> Using procedural methods only (without objects), such structures
> would be difficult to emulate;
>
>> So, for now, I'm taking a look at Beginning Java Objects. Even though
> "Java"
>> is in the title--hence my previous question--much of the book is about
>> the
>> general ideas, with little or no connection to Java itself. I think the
> book
>> devotes a lot of attention to the issue I just mentioned.
>
> The basic ideas of OOP are pretty general;
>
>> Again, I appreciate the responses and the reading suggestions. I'm not a
>> programmer (yet!), but I am an educator, and I know that the teaching
>> resources available today for Java (beginners) are definitely superior to
>> those available for Delphi (and probably most other languages, too). So,
> I'm
>> glad folks sent along a couple of the older resources for Delphi that
>> they
>> thought were both useful and still up to date enough to be valuable.
>
> It's true that there is a lot of stuff on Java and its widely used,
> but I have to say that I prefer to work in Delphi;
> I am moving to Java/C# in order to have work,
> not because I particularly want to;
> (In Italy Delphi is not very widespread)
> C# is also well constructed as far as OOP is concerned and is close to
> Java;
>
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