From: Christopher Carver <ccarver0@...>
Date: 2009-06-16T01:56:43+09:00
Subject: Re: confusion about object method scoping

Thanks!  That worked.  It's actually computing the factorial (sum of
all digits leading up to the argument).  Can you give me a term for
what is going on in your example with the "<<" notation?  I'd like to
read about it and understand it more.  I'm a bit new to Ruby.

Thanks a lot for the help!

Chris

On Mon, Jun 15, 2009 at 12:45 PM, Robert
Klemme<shortcutter@googlemail.com> wrote:
> 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
>
>
> --
> remember.guy do |as, often| as.you_can - without end
> http://blog.rubybestpractices.com/
>
>