From: Brian Candler <b.candler@...>
Date: 2009-11-16T19:27:02+09:00
Subject: Re: Newbie question:  Defining a numeric type

Seebs wrote:
> I think I'm thinking something like the Comparable mixin; sort of a
> "I have a to_i, make me a number" module.

You could just delegate to the number:

class Foo
  def initialize(n)
    @n = n
  end
  def to_int
    @n
  end
  def method_missing(*args)
    to_int.send(*args)
  end
end

f = Foo.new(12)
puts f + 3
puts 2 + f

Note that there is a subtle distinction between to_int and to_i, as 
there is between to_str and to_s. I think you want to_int here, since 
you are declaring that your object is, to all intents and purposes, an 
integer.

You could also look at the #coerce method, but I don't think it's needed 
here.
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