From: Clifford Heath <no@...>
Date: 2008-02-12T16:04:57+09:00
Subject: Subclassing Integer; solved!

Folk,

Refer to <http://www.ruby-forum.com/topic/96434> for the context.

I'm doing some metaprogramming where I wanted folk to be able to
subclass Integer, for example: "class Year < Integer; ... end".
You can't do this with Integer in a sensible way, because Integers
are value types in Ruby, and don't support the new() method.

However, I came up with the following cunning bit of code, which
seems to work. The code is also here: <http://pastie.caboo.se/150741>.
I use BasicObject from Facets, which isn't the only way to get that,
you might have 1.9 for example :-).

Please comment,

Clifford Heath.

require "facets/basicobject" unless Object.const_defined? :BasicObject

class Integer
  class BoxedInteger < BasicObject
    private
    attr_accessor :__value

    def self.new(*a)
      super *a
    end

    def initialize(v)
      @__value = v.to_i
    end

    def method_missing(meth, *args, &block)
      __value.send meth, *args, &block
    end
  end

  def self.inherited(subclass)
    def subclass.new(i)
      BoxedInteger.new(i)
    end
  end
end