In article <9t2ums$t56$1 / redenix.uni-muenster.de>, "Masanori Fujita"
<fujita / uni-muenster.de> wrote:

> Hello.
> 
> I'm new to Ruby and hav just tried out an example from "Programming
> Ruby" in which the +-Operator of the Fixnum-Class should be redefined.
> 
> I executed the following code:
> 
> class Fixnum
>   alias oldPlus +
>   def +(other)
>     oldPlus(other).succ
>   end
> end
> 
> puts 1 + 2
> 
> The interpreter seems to end with a stack overflow. So what is the
> problem with this piece of code?

I cut and pasted your code into a file and it works fine with my
interpreter (1.6.5 on linux).  Which version are you running?