Re: a modular design question

From:

Robert Klemme <shortcutter@googlemail.com>

Newsgroups:

comp.lang.java.programmer

Date:

Mon, 18 Sep 2006 15:09:14 +0200

Message-ID:

<4n7k3qF93262U1@individual.net>

On 18.09.2006 14:42, Shawn wrote:

Hi,

I have a modular design(code-reusage) question. In order to make my
point clear, I have made up the following fake situations:

Last year in a project, I have written a class Person:

<snip/>

What should I do? Suppose the Animal class has 90% code same as the
Person class. I can think of several answers:
(A) Using Person class as a guide, quickly write Animal class. Because
there is a guide, so writing Animal class won't take as much time as
writing Person class.

Problems: I feel there is no code-reusage at all, strictly speaking.

(B)Using abstract class: write an abstract class which captures the
common features of both Person class and Animal class. Then write the
subclasses of it, which are Person class and Animal class.

Problems: now I have to change the code (Person class) in last year's
project. I have finished and delivered the project already.

IMHO the choice depends largely on how related those projects are and
how many of these cases you have. If you feel you get frequently into
this situation or these projects are somehow related it might be
reasonable to go with A and refactor Person to inherit from a base class
that you stick into some form of library (which is used by both
projects). However, if it is just these two classes it's probably not
worth while and copy and paste is a better solution. (This is also a
form of code reuse albeit not the one commonly intended.)

Kind regards

robert