From: "David A. Black" <dblack@...>
Date: 2004-08-13T20:59:11+09:00
Subject: Re: Relationship between classes

Hi --

On Fri, 13 Aug 2004, Luke A. Kanies wrote:

> ...
>                  :chown => [
>                      [:owner, :file],
>                      proc { |object|
>                          Blink::Operation::Chown.new(
>                              :owner => proc { |object| object[:uid] },
>                              :file => proc { |object| object[:file] }
>                          )
>                      }
>                  ],
> ...
> 
> This stores my three key pieces of information:  What the object calls the 
> operation (so it knows how to execute it on itself later), what attributes 
> are necessary in order to create an instance of the operation, and how to 
> actuallly instantiate the operation.
> 
> I am currently storing all of these in a big hash in each object class 
> definition.
> 
> This seems really inelegant, though, and it causes some weird side effects 
> in my thinking.
> 
> Is there some better way to store these relationships, without causing 
> leaking of the object interface into the operation definition?

Maybe create some classes to wrap all of this in, so that you would
then do something like:

  obj.add_operation(:chown) do |op|
    op.attributes = [:owner,:file]
    op.action = lambda {|object| .... }
    ...
  end

and so on.  That might scale more nicely, and allow you to easily add
ways to query and view things as you go.


David

-- 
David A. Black
dblack@wobblini.net