From: Robert Klemme <shortcutter@...>
Date: 2009-06-16T01:45:13+09:00
Subject: Re: confusion about object method scoping

On 15.06.2009 18:31, Christopher Carver wrote:
> Hello,
> 
> I am defining a class.  That class has several methods.  In one of the
> class methods I'm trying to use a previously defined method.  It's
> throwing an exception.  Here's some code that demonstrates my problem.
>  Am I really unable to have a class use some of it's own methods if
> they've already been defined?  Thanks in advance!
> 
> class Calculator
> 
>  private
>  def add(x,y)
>    x+y
>  end
> 
>  public
>  def Calculator.factorial(x)
>    result = 0
> 
>    (1..x).each { |number|
>      result = add(result,number)
>    }
> 
>    result
>  end
> 
> end
> 
> puts Calculator.factorial()
> 

You are mixing class and instance methods.  You need to make add also a 
class method, e.g. by doing something like this

class Calculator
   class <<self
     def factorial(x)
       result = 0
       (1..x).each { |number|
        result = add(result, number)
       }
       result
     end

   private
     def add(x,y) x + y end
   end
end

Btw, the naming "factorial" seems a bit odd for a sum.

Kind regards

	robert


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