What is/is not considered to be good OO programming

[Tony Marston]

Several months ago I started a thread with the title "What is/is not
considered to be good OO programming" which started a long and
interesting discussion.

I have condensed the arguments into a single article which can be
viewed at

http://www.tonymarston.net/php-mysql/good-bad-oop.html

I fully expect this to be the start of another flame war, so sharpen
your knives and get stuck in!

Tony (you do it your way and I'll do it better) Marston

http://www.tonymarston.net/

[Jochen Daum]

Re: What is/is not considered to be good OO programming

On 3 Dec 2003 05:30:25 -0800, tony@marston-home.demon.co.u k (Tony
Marston) wrote:
[color=blue]
>Several months ago I started a thread with the title "What is/is not
>considered to be good OO programming" which started a long and
>interesting discussion.
>
>I have condensed the arguments into a single article which can be
>viewed at
>http://www.tonymarston.net/php-mysql/good-bad-oop.html
>[/color]

Thats great. I'll be reading it after my holiday and possibly contact
you by email, if you don't mind.

Jochen
--
Jochen Daum - CANS Ltd.
PHP DB Edit Toolkit -- PHP scripts for building
database editing interfaces.

http://sourceforge.net/projects/phpdbedittk/

[J0hn Sm1th]

Re: What is/is not considered to be good OO programming

Tony Marston wrote:[color=blue]
> Several months ago I started a thread with the title "What is/is not
> considered to be good OO programming" which started a long and
> interesting discussion.
>
> I have condensed the arguments into a single article which can be
> viewed at
> http://www.tonymarston.net/php-mysql/good-bad-oop.html
>
> I fully expect this to be the start of another flame war, so sharpen
> your knives and get stuck in!
>
> Tony (you do it your way and I'll do it better) Marston
> http://www.tonymarston.net/[/color]

Hey that's a really well written (or put together) document. I'll be
saving that for good use.

[André Næss]

Re: What is/is not considered to be good OO programming

Tony Marston:
[color=blue]
> Several months ago I started a thread with the title "What is/is not
> considered to be good OO programming" which started a long and
> interesting discussion.
>
> I have condensed the arguments into a single article which can be
> viewed at
> http://www.tonymarston.net/php-mysql/good-bad-oop.html
>
> I fully expect this to be the start of another flame war, so sharpen
> your knives and get stuck in!
>
> Tony (you do it your way and I'll do it better) Marston
> http://www.tonymarston.net/[/color]

I just think it's funny that you still don't understand object composition.
In your article you write: "How do you share code in OO systems? Through
inheritance.", not even mentioning object composition. Object composition
was also the crux of my argument, i.e.: where you see only inheritance, I
see inheritance and composition. From this we can only deduce that you in
fact did not properly understand my argument. That doesn't make the
discussion any easier.

But then again, most beginners in OOP face this particular problem, they
overuse inheritance because that's usually the first thing they learn, and
once they get the hang of it, they won't let go.

André næss

[Philipp Lenssen]

Re: What is/is not considered to be good OO programming

André Næss wrote:
[color=blue]
> Tony Marston:
>[/color]
[color=blue][color=green]
> >
> > I have condensed the arguments into a single article which can be
> > viewed at
> > http://www.tonymarston.net/php-mysql/good-bad-oop.html
> >[/color][/color]
[color=blue]
>
> I just think it's funny that you still don't understand object
> composition. In your article you write: "How do you share code in OO
> systems? Through inheritance.", not even mentioning object
> composition. Object composition was also the crux of my argument,
> i.e.: where you see only inheritance, I see inheritance and
> composition. From this we can only deduce that you in fact did not
> properly understand my argument. That doesn't make the discussion any
> easier.
>[/color]

I was thinking the same. I saw the article, looked for "compositio n",
couldn't find it, and went away.

--
Google Blogoscoped

http://blog.outer-court.com

[Tony Marston]

Re: What is/is not considered to be good OO programming

André Næss <andrena.spamre allysucks@ifi.u io.no> wrote in message news:<bqn4ko$3k l$1@maud.ifi.ui o.no>...[color=blue]
> Tony Marston:
>[color=green]
> > Several months ago I started a thread with the title "What is/is not
> > considered to be good OO programming" which started a long and
> > interesting discussion.
> >
> > I have condensed the arguments into a single article which can be
> > viewed at
> > http://www.tonymarston.net/php-mysql/good-bad-oop.html
> >
> > I fully expect this to be the start of another flame war, so sharpen
> > your knives and get stuck in!
> >
> > Tony (you do it your way and I'll do it better) Marston
> > http://www.tonymarston.net/[/color]
>
> I just think it's funny that you still don't understand object composition.
> In your article you write: "How do you share code in OO systems? Through
> inheritance.", not even mentioning object composition.[/color]

Because I have looked at definitions and examples of object
composition and deduced that it would serve no useful purpose in my
infrastructure.

To quote one reference: http://www.eagle-software.com/object.htm

"Object composition allows you to group components together, creating
a new component."

I do not see where I can use this technique, or what advantage it
would bring, therefore I am not going to waste any time on it.

To quote another reference:

http://brighton.ncsa.uiuc.edu/~prajlich/T/node14.html

"The disadvantage of object composition is that the behavior of the
system may be harder to understand just by looking at the source code.
A system using object composition may be very dynamic in nature so it
may require running the system to get a deeper understanding of how
the different objects cooperate."

As I do not like writing complicated software that is difficult to
understand this whole idea sounds like a no-no to me. I prefer to
follow the KISS principle.

From the same article:

"Most designers overuse inheritance, resulting in large inheritance
hierarchies that can become hard to deal with."

If you look at my code you will see that I do not have a large
inheritance hierarchy. I have just one superclass and one layer of
subclass, therefore you cannot say that I am overusing inheritance.

[color=blue]
> Object composition
> was also the crux of my argument, i.e.: where you see only inheritance, I
> see inheritance and composition. From this we can only deduce that you in
> fact did not properly understand my argument.[/color]

You argument is irrelevant as it serves no useful purpose when
discussing a single abstract class.

Tony Marston

http://www.tonymarston.net/

[color=blue]
> That doesn't make the discussion any easier. But then again, most beginners
> in OOP face this particular problem, they overuse inheritance because that's
> usually the first thing they learn, and once they get the hang of it, they
> won't let go.
>
> André næss[/color]

[Tony Marston]

Re: What is/is not considered to be good OO programming

"Philipp Lenssen" <info@outer-court.com> wrote in message news:<bqn8cf$23 206g$1@ID-203055.news.uni-berlin.de>...[color=blue]
> André Næss wrote:
>[color=green]
> > Tony Marston:
> >[/color]
>[color=green][color=darkred]
> > >
> > > I have condensed the arguments into a single article which can be
> > > viewed at
> > > http://www.tonymarston.net/php-mysql/good-bad-oop.html
> > >[/color][/color]
>[color=green]
> >
> > I just think it's funny that you still don't understand object
> > composition. In your article you write: "How do you share code in OO
> > systems? Through inheritance.", not even mentioning object
> > composition. Object composition was also the crux of my argument,
> > i.e.: where you see only inheritance, I see inheritance and
> > composition. From this we can only deduce that you in fact did not
> > properly understand my argument. That doesn't make the discussion any
> > easier.
> >[/color]
>
> I was thinking the same. I saw the article, looked for "compositio n",
> couldn't find it, and went away.[/color]

Just for you I have added a section on object composition. I hope you like it.

http://www.tonymarston.net/php-mysql/good-bad-oop.html#2003-12-05

Kiss, kiss

Tony Marston

http://www.tonymarston.net/

[André Næss]

Re: What is/is not considered to be good OO programming

Tony Marston:
[color=blue][color=green]
>> Object composition
>> was also the crux of my argument, i.e.: where you see only inheritance, I
>> see inheritance and composition. From this we can only deduce that you in
>> fact did not properly understand my argument.[/color]
>
> You argument is irrelevant as it serves no useful purpose when
> discussing a single abstract class.[/color]

I wasn't discussing a single abstract class. I was discussing a solution to
a problem. The single abstract class and proliferation of new classes is
*your* solution. I tried to argue that a different, and IMO better approach
was possible. You didn't bother to learn about object composition until
*now*, yet you disagreed with my idea of using it in your case. In other
words, you had decided that your solution *is* the best even before you
started the discussion, despite the fact that you did not know much about
OO.

André Næss

[Doug Hutcheson]

Re: What is/is not considered to be good OO programming

"Tony Marston" <tony@marston-home.demon.co.u k> wrote in message
news:7588a50f.0 312050544.1dad5 b57@posting.goo gle.com...[color=blue]
> "Philipp Lenssen" <info@outer-court.com> wrote in message[/color]
news:<bqn8cf$23 206g$1@ID-203055.news.uni-berlin.de>...[color=blue][color=green]
> > André Næss wrote:
> >[color=darkred]
> > > Tony Marston:
> > >[/color]
> >[color=darkred]
> > > >
> > > > I have condensed the arguments into a single article which can be
> > > > viewed at
> > > > http://www.tonymarston.net/php-mysql/good-bad-oop.html
> > > >[/color]
> >[color=darkred]
> > >
> > > I just think it's funny that you still don't understand object
> > > composition. In your article you write: "How do you share code in OO
> > > systems? Through inheritance.", not even mentioning object
> > > composition. Object composition was also the crux of my argument,
> > > i.e.: where you see only inheritance, I see inheritance and
> > > composition. From this we can only deduce that you in fact did not
> > > properly understand my argument. That doesn't make the discussion any
> > > easier.
> > >[/color]
> >
> > I was thinking the same. I saw the article, looked for "compositio n",
> > couldn't find it, and went away.[/color]
>
> Just for you I have added a section on object composition. I hope you like[/color]
it.[color=blue]
>
> http://www.tonymarston.net/php-mysql...tml#2003-12-05
>
> Kiss, kiss
>
> Tony Marston
> http://www.tonymarston.net/[/color]

Tony,
A trifle defensive <grin>, but wholly correct. As another 25+ programmer, I
can state without too much fear of contradiction that the customer pays me
to solve his problem, not to write code which meets the approval of the
paradigm police.
More power to you, you rabid radical you!
Cheers,
Doug Hutcheson

[Matty]

Re: What is/is not considered to be good OO programming

Doug Hutcheson wrote:
[color=blue]
> "Tony Marston" <tony@marston-home.demon.co.u k> wrote in message
> news:7588a50f.0 312050544.1dad5 b57@posting.goo gle.com...[/color]

<snip>
[color=blue][color=green]
>>
>> http://www.tonymarston.net/php-mysql...tml#2003-12-05
>>[/color][/color]

<snip>
[color=blue]
> Tony,
> A trifle defensive <grin>, but wholly correct. As another 25+ programmer,
> I can state without too much fear of contradiction that the customer pays
> me to solve his problem, not to write code which meets the approval of the
> paradigm police.
> More power to you, you rabid radical you!
> Cheers,
> Doug Hutcheson[/color]

Wow, it's come back to life again!

Asbestos manufacturers everywhere must be looking forwards
to this one!

;p

Matt

[Matty]

Re: What is/is not considered to be good OO programming

Matty wrote:

[color=blue]
> Wow, it's come back to life again!
>
> Asbestos manufacturers everywhere must be looking forwards
> to this one!
>
> ;p
>
> Matt[/color]

FWIW, I still think it's better to have 12 different instances,
rather than 12 different classes <duck />... Not read it all yet,
just a quick search! I'll have a good read through tomorrow, but
I do think there aren't sufficient differences between tables in a
database to justify having a separate class to handle each table,
when a separate instance of a suitably generic class would handle it
OK.

I am definitely a TMTOWTDI kind of person, though, and I do agree
that fundamentally, if the software works, then it's good.

Matt

[Matty]

Re: What is/is not considered to be good OO programming

>> "Tony Marston" <tony@marston-home.demon.co.u k> wrote in message[color=blue][color=green]
>> news:7588a50f.0 312050544.1dad5 b57@posting.goo gle.com...[/color]
>
> <snip>
>[color=green][color=darkred]
>>>
>>> http://www.tonymarston.net/php-mysql...tml#2003-12-05
>>>[/color][/color][/color]

(Yet Another Follow Up...)

Can't help wondering what the object composition argument was, and how
on earth you could do it in a logical manner.

A table "has a" page of records?

A page of records "has a" table (what would it do if it didn't?)

Personally, yeah, I think composition isn't the way to do it...

/me thinks How about a table "has a" table perhaps???


;p

Matt

[Tony Marston]

Re: What is/is not considered to be good OO programming

André Næss <andrena.spamre allysucks@ifi.u io.no> wrote in message news:<bqq53c$c6 9$1@maud.ifi.ui o.no>...[color=blue]
> Tony Marston:
>[color=green][color=darkred]
> >> Object composition
> >> was also the crux of my argument, i.e.: where you see only inheritance, I
> >> see inheritance and composition. From this we can only deduce that you in
> >> fact did not properly understand my argument.[/color]
> >
> > You argument is irrelevant as it serves no useful purpose when
> > discussing a single abstract class.[/color]
>
> I wasn't discussing a single abstract class. I was discussing a solution to
> a problem. The single abstract class and proliferation of new classes is
> *your* solution. I tried to argue that a different, and IMO better approach
> was possible.[/color]

It may seem better in your opinion, but to my mind it is different
without any obvious benefits, so there is no point in changing.
[color=blue]
> You didn't bother to learn about object composition until
> *now*, yet you disagreed with my idea of using it in your case.[/color]

Object composition is not listed among the principles of OOP, so I
ignored it. When I did read about it the first thing that I saw was
that it was considered as an alternative method of dealing with
complex hierarchies. As I do not have a complex hierarchy (just two
levels) there seems no point in investigating it any further.
[color=blue]
> In other
> words, you had decided that your solution *is* the best even before you
> started the discussion,[/color]

I never said it was the best, I merely said that it is simple and it
works. As a follower of the KISS principle this is VERY important. Why
waste time on a complex solution if a simple one works?
[color=blue]
> despite the fact that you did not know much about OO.
>
> André Næss[/color]

It is true that I have not been taught any OO, but that means that I
have not been taught the wrong things. What I have read about OO tells
me that objects are not that much different to components, and as I
have been working with a component-based development language for the
last 10 years all I did was to take my component-based design and
convert it to object-based. Simple and effective.

The fact that I do not do OOP in the way that you do it is irrelevant.
I can achieve rapid results my way, so my way is good for me (and a
few others according to the emails I have received).

Tony Marston

http://www.tonymarston.net/

[Philipp Lenssen]

Re: What is/is not considered to be good OO programming

Tony Marston wrote:
[color=blue]
> "Philipp Lenssen" <info@outer-court.com> wrote in message
> news:<bqn8cf$23 206g$1@ID-203055.news.uni-berlin.de>...[color=green]
> > André Næss wrote:
> >[/color][/color]
[color=blue][color=green]
> >
> > I was thinking the same. I saw the article, looked for
> > "compositio n", couldn't find it, and went away.[/color]
>
> Just for you I have added a section on object composition. I hope you
> like it.
>
> http://www.tonymarston.net/php-mysql...tml#2003-12-05
>[/color]

You should differentiate between "has a" and "is a". I believe I
recently posted this here and the idea is neither mine nor new.

Inheritance examples in books often go by the examples of employees.
And employee "is a type of" person. So it would not make sense to use
object composition. (Not if person and employee are intended to be the
same anyway.) Because an employee shares attributes of a person but
includes his own.

Now let's say I have a class "webpage". Now this "webpage" has a
complex module "binary_ima ge" which will render images. You would use
simple object composition by creating a new instance of "binary_ima ge"
within "webpage".

Why is it composited and not inherited?
Because the webpage "has a" binary image. However, it's wrong to say
binary_image "is a type of" webpage. 'Cause it's not.

This was just an example. Usually I don't use global instances of
objects either in a class. Usually they just go right into the
function. E.g. using the file-system object from within a class on a
Windows server. Or handling XML.

And object composition structures the code and can make it more
readable. It's often more natural. But whatever approach suits you.
Don't forget however that if you're working in a team you can't just
say "my approach is better 'cause I like it and everyone should code
the way they want", because code must be managed by others. You
wouldn't expect your code to be rewritting from scratch or highly
refactored if you were sick for a week and someone else had to go
through it. So you should write code in ways accepted and used in your
team, and to find the best solution you must argue beyond personal
taste. Sometimes, you may even need to compromise.

[Tony Marston]

Re: What is/is not considered to be good OO programming

"Doug Hutcheson" <doug.nospam.hu tcheson@nrm.qld .gov.au> wrote in message news:<B%NAb.104 2$hX1.34374@new s.optus.net.au> ...[color=blue]
> "Tony Marston" <tony@marston-home.demon.co.u k> wrote in message
> news:7588a50f.0 312050544.1dad5 b57@posting.goo gle.com...[color=green]
> > "Philipp Lenssen" <info@outer-court.com> wrote in message[/color]
> news:<bqn8cf$23 206g$1@ID-203055.news.uni-berlin.de>...[color=green][color=darkred]
> > > André Næss wrote:
> > >
> > > > Tony Marston:
> > > >[/color][/color]
>[color=green][color=darkred]
> > > > >
> > > > > I have condensed the arguments into a single article which can be
> > > > > viewed at
> > > > > http://www.tonymarston.net/php-mysql/good-bad-oop.html
> > > > >[/color][/color]
>[color=green][color=darkred]
> > > >
> > > > I just think it's funny that you still don't understand object
> > > > composition. In your article you write: "How do you share code in OO
> > > > systems? Through inheritance.", not even mentioning object
> > > > composition. Object composition was also the crux of my argument,
> > > > i.e.: where you see only inheritance, I see inheritance and
> > > > composition. From this we can only deduce that you in fact did not
> > > > properly understand my argument. That doesn't make the discussion any
> > > > easier.
> > > >
> > >
> > > I was thinking the same. I saw the article, looked for "compositio n",
> > > couldn't find it, and went away.[/color]
> >
> > Just for you I have added a section on object composition. I hope you like[/color]
> it.[color=green]
> >
> > http://www.tonymarston.net/php-mysql...tml#2003-12-05
> >
> > Kiss, kiss
> >
> > Tony Marston
> > http://www.tonymarston.net/[/color]
>
> Tony,
> A trifle defensive <grin>, but wholly correct. As another 25+ programmer, I
> can state without too much fear of contradiction that the customer pays me
> to solve his problem, not to write code which meets the approval of the
> paradigm police.
> More power to you, you rabid radical you!
> Cheers,
> Doug Hutcheson[/color]

People tend to describe me more as revolting than rebelling. Is there
a difference? :)

Tony Marston

http://www.tonymarston.net/