From: Robert Klemme <shortcutter@...>
Date: 2010-07-10T06:15:02+09:00
Subject: Re: from functions to classes, where should I start?

On 09.07.2010 19:11, Jay wrote:
> Hi JaordZZ,
> I began software development using OOP can't recall any books to
> recommend. I would encourage you to think critically about when to use
> OOP, rather than doing it simply because of Agile dogma.  When
> reviewing my code, I've often found that I tend to use classes for
> everything -- just out of habit (and due to a heavy Java background).
> When coding, I now try to ask myself, "Does this code represent
> something that benefits from OOP, or should it exist as a function(or
> Module or static method)?".
>
> Here are some of the most common reasons to consider OOP:
>
> 1) Making state information handy to the functions that need it.
> If you find yourself passing the same data in as parameters to related
> functions, then consider wrapping the data and functions up into a
> class.

The key word for this is "encapsulation".  I believe it is the most 
important aspect of OO.

> 2) Organizing large amounts of code
> OOP allows you to present public interfaces that simplify the usage of
> code.  This is very helpful for large projects, but not usually
> necessary for smaller scripts and projects.

I think this is normally named "information hiding".  I use it even for 
smaller scripts.

> 3) Use of inheritance or polymorphism
> If you want to benefit from subclassing objects.

IMHO inheritance is overrated (or maybe overused).  Often people turn to 
inheritance where composition would be a better choice.  But I agree, 
this is another important aspect of OO.

> And some common reasons to consider your current approach:
> 1) You are already using it and it works (or does it?)
> 2) There is a small performance penalty with each object that is
> instantiated
>
>
> I know this is very oversimplified, but my lunch break is ending
> soon.  ;-)

... and I have to go to bed now. :-)

Cheers

	robert


PS: JaordZZ, a book or tutorial about patterns might help.  See here for 
a start:
http://en.wikipedia.org/wiki/Design_pattern_%28computer_science%29

-- 
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/