Hal Fulton wrote:
....
>> 1.6.x is the earliest version I've worked with... I remember trying 
>> this when I first started out with ruby :) I thought it was a nifty 
>> trick. You still can't define singleton methods though, just add 
>> instance variables. Though, I suppose you could add a proc object as 
>> an instance variable.
> 
> 
> The last time I tried this, it was a little deceptive. A variable
> that you added to one Fixnum was the same for all Fixnums.

Well with 1.8.1 you get

---
class Fixnum
   def bla=(rhs)
     @bla = rhs
   end
   def bla
     p @bla
   end
end

2.bla = true
3.bla = false

2.bla # true
---

/Christoph