From: dblack@...
Date: 2003-05-14T06:26:19+09:00
Subject: Re: [OO design] Objects VS Datastructures

Hi --

On Wed, 14 May 2003, Simon Vandemoortele wrote:

> The problem I see in this setup is that my 'Objects' are very passive;
> they are not much more than datastructures with an attitude. Their whole
> interface consists of setters and getters. I've been wondering if this
> is still OO ? Shouldn't I be sending 'messages' instead of "taking some
> 'Object', pulling out some information to shove it somewhere else" ?
>
> What are your thoughts on this matter ? Am I doing procedural
> programming in a OO language or is this an unavoidable consequence of
> the addressbook problem I am trying to solve ?
>
> Corollary:  It has also occurred to me that Contact#setName(aString)
>             where Contact checks if the name satisfies certain
>             conditions might not be the best setup since a 'name' is not
>             string; it is much narrower than that (in my
>             implementation). Maybe I'd better create a Name class that
>             represents a 'name' object and enforces it's integrity.
>             Doing that for all Contact's attributes would reduce it's
>             responsibilities to the point where it would barely differ
>             from a Hash, thus exacerbating the question above.

Rather than Contact#setName (or even Contact#set_name :-) you'd
probably be better off leveraging Ruby's idiomatic set/get mechanism:

  Contact#name     # getter
  Contact#name=    # setter

(which you can do easily with the attr_* family of shortcuts, or by
hand if you need more complexity).

Technically this is no more or less of a "message"-based way than what
you're doing now (since all method calls in Ruby are based on the
message-sending model), but it's a better fit with the language and
might start to give you a stronger sense of the Contact objects (and
others) as more than data structures.


David

-- 
David Alan Black
home: dblack@superlink.net
work: blackdav@shu.edu
Web:  http://pirate.shu.edu/~blackdav