From: Intransition <transfire@...>
Date: 2010-06-20T00:34:14+09:00
Subject: Re: General Ruby OOP question



On Jun 19, 9:56 am, "Paul A." <cyril.st...@gmail.com> wrote:
> Hello,
>
> I have a general question about OOP with Ruby.  If I have 2 class: Home
> and Person for instance, such as:
>
> >> class Home
> >>   def initialize
> >>     @person1 = Person.new
> >>     @person2 = Person.new
> >>     # ...
> >>   end
>
> >>   def open_a_window; end
> >>   # ...
> >> end
> >> class Person
> >>   def play_wii_game; end
> >> end
>
> Then, a home instance can include a lot of people. And that's cool.  And
> a home instance can apply action on a person using a method just like:
> @person2.play_wii_game
>
> But if a person want to open a window in its home?  Here, with a such
> design it's impossible, isn't it.
>
> So to allow this kind of action, I think we need to pass as parameter
> self inside Home initialization process, becoming:
>
>
>
> >> class Home
> >>   def initialize
> >>     @person1 = Person.new(self)
> >>     @person2 = Person.new(self)
> >>     # ...
> >>   end
>
> >>   def open_a_window; end
> >>   # ...
> >> end
> >> class Person
> >>   def initialize(home)
> >>     @home = home
> >>   end
>
> >>   def open_a_window
> >>     @home.open_a_window
> >>   end
>
> >>   def play_wii_game; end
> >> end
>
> Now, a instantiated person can do it using open_a_window proxy method.
> And any other proxifyable home's methods.
>
> But is it ethics? I mean, is that lawful under the principles of
> object-oriented programming. Maybe this is so much power, to pass self
> inside person instance inside its home... 'cause it's almost as if there
> was no class, no partitioning.
>
> What do you think about this?
> Thanks for any considerations.

It's fine. But why is Home creating people? Perhaps they should be
added to a home? In which case you could create a home and then a
person with a home and the person would be automatically added to that
home.

  home = Home.new
  person1 = Person.new(home1)

 Or you could create both the home and person separately but when you
add the person to the home they will pick up a reference to it.

  home = Home.new
  person1 = Person.new
  home << person1

In Home:

  class Home

    def <<(person)
      @persons << person
      person.home = self
    end

~trans