From: Tobias Weber <towb@...>
Date: 2008-05-25T23:19:46+09:00
Subject: Re: How to model something

In article <F7E21685-9F99-48F0-A3AC-990A18B0294E@mwilden.com>,
 Mark Wilden <mark@mwilden.com> wrote:

> [Note:  parts of this message were removed to make it a legal post.]

?

> > I could have 'if gender' in every accessor
> 
> That seems like the simplest approach. The person object is the one  
> who's creating this restriction - weight shouldn't know about gender  
> and gender shouldn't know about weight. Wouldn't that only affect one  
> accessor - weight?

In the example, yes. In reality it's 3 attributes and writing is 
forbidden as well. I implemented it using one class and an Integer for 
the genders and it got pretty messy as (storage) space needs to 
manufacture persons and therefore write female's weight where it 
normally wouldn't be allowed.

I worked around that using set_instance_variable but felt awful.

So I rewrote everything using the state pattern, but with a Struct 
containing the attributes being passed around between state instances. 
Even uglier code.

I hate Java, but its protected package access would help with this.

-- 
  Tobias Weber