From: Marnen Laibow-Koser <marnen@...>
Date: 2009-11-20T02:48:42+09:00
Subject: Re: Re-opening an existing module and changing a method

Aldric Giacomoni wrote:
> "I hear and I forget; I see and I remember; I do and I understand."
> Wouldn't it be nice if it were that simple - clearly they did not know
> about the subtle art of debugging.
> 
> So, I'm trying to hack at the math module.
> Expected:
>>> Math.sqrt(2)
> => sqrt(2)
> Actual result, mileage does not vary:
>>> Math.sqrt(2)
> => 1.4142135623731
> 
> require 'mathn'
> module Math
>   alias :old_sqrt :sqrt
>   def sqrt x
>     result = old_sqrt x
>     if result.is_a? Float
>       "sqrt(#{x})"
>     else
>       result
>     end
>   end
> end
> 
> puts Math.sqrt(2)
> 
> I had originally not attempted an alias, I just did "result = super x"
> but it didn't really amount to much, either.
> Where am I thinking about this wrong?

Looks fine to me.  Does old_sqrt actually return a Float or some other 
numeric type?

Actually, why use type checking at all?  Why not change the condition to 
use kind_of or simply test result.to_i - result == 0 ?


Best,
--
Marnen Laibow-Koser
http://www.marnen.org
marnen@marnen.org
-- 
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