From: Bob Sidebotham <bob@...>
Date: 2004-10-01T10:10:10+09:00
Subject: Can you rewrite this in a better way?

I would like to define a method that can be used to compactly define 
some items of interest (here called "fields") for subclasses. It's used 
like this:

class B < A
   fields :a, :b, :c
end

class C < A
   fields :x, :y
end

p B.new.fields                => [:a, :b, :c]
p C.new.fields                => [:x, :y]

Here are two definitions for class A that support these semantics:

---#1------------------------------------------------

class A
   def self.fields(*fields)
     @fields = fields
     def fields
       self.class.getFields
     end
   end

   private
   def self.getFields
     @fields
   end
end

---#2------------------------------------------------

class A
   def self.fields(*fields)
     eval "def fields
       [#{fields.collect{|f| ':' + f.to_s}.join(',')}]
     end"
   end
end

-----------------------------------------------------

Is there a better way (more efficient, shorter and/or clearer) to do this?

Thanks!
Bob Sidebotham