From: Robert Klemme <shortcutter@...>
Date: 2012-09-28T01:42:16+09:00
Subject: Re: Subclassing Date

On Thu, Sep 27, 2012 at 2:30 PM, Damián M. González
<lists@ruby-forum.com> wrote:
>> Why are you subclassing Date in the first place?
>
>  Well, the class Dia(It's day in spanish) represent a day. Each instance
> of this class have like 10 inst. variables. I wanted to subclass Date
> because I want to be available +() or -() or cweek() to a Dia instance,
> in the way that it behave like a Date object does.

Then better use composition as has been suggested.  Inheriting core
classes is rarely a good idea.  What you have is actually something
else which happens to have a data attached to it as well.  If you need
numeric operations one of my blog articles might help you to implement
operators properly:

http://blog.rubybestpractices.com/posts/rklemme/019-Complete_Numeric_Class.html

Cheers

robert


-- 
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