From: Gary Wright <gwtmp01@...>
Date: 2007-05-03T13:43:36+09:00
Subject: Re: simple subclass question


On May 2, 2007, at 2:57 PM, Ball, Donald A Jr (Library) wrote:
> In the superclass, I want a chunk of code that
> initializes a class instance variable in itself and each of its class
> descendents.

You can use #inherited to trigger your own class initialization:

class Base
   class <<self
     def inherited(other)
       other.instance_eval { initialize_class }
     end
     def initialize_class
       @foo = 42
     end
     attr_accessor :foo
   end
   initialize_class
end

class Subclass < Base
   puts "foo is #{@foo}"       # 42
end

puts Subclass.foo             # 42
puts Class.new(Base).foo      # 42



Gary Wright