From: dblack@...
Date: 2006-04-27T10:56:23+09:00
Subject: Re: Extending Methods

Hi --

On Thu, 27 Apr 2006, Daniel Harple wrote:

> On Apr 27, 2006, at 3:26 AM, Geoff Stanley wrote:
>
>> 1) The child classes wouldn't do
>> anything; They'd have to be hooked into the main program somehow...
>> troublesome and [...]
>
> 1) Use Class#inherited
>
> class Parent
>  @@children = []
>  def self.children
>    @@children
>  end
>
>  def self.inherited(child)
>    @@children << child
>  end
> end
>
> class Child < Parent
> end
>
> class Child2 < Parent
> end
>
> Parent.children # => [Child, Child2]
> # initialize each plugin ...

Although....

   class GrandChild < Child
   end

   Parent.children # => [Child, Child2, GrandChild]

You could get around it like this:

   def self.inherited(child)
     def child.inherited(grandchild)
     end
     @@children << child
   end

:-) or maybe use an instance variable instead of a class variable,
since you really want to track the state of a single object:

   class Parent
     def self.children
       @children
     end

     def self.inherited(child)
       @children ||= []
       @children << child
     end
   end


David

-- 
David A. Black (dblack@wobblini.net)
Ruby Power and Light, LLC (http://www.rubypowerandlight.com)

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