From: ahoward <ahoward@...>
Date: 2002-12-05T00:10:31+09:00
Subject: Re: Class variables problem

On Wed, 4 Dec 2002, Useko Netsumi wrote:

> Why would the following did not work?
>
> class Test
>     def Calc(x)
>         return @rate*x
>     end
> end
>
> class Fred < Test
>     @rate = 10
> end
>

> puts Fred.Calc(12)

this has been called like a class method, but Calc is an instance method.

additionally Calc should not be capitalized, else it is also a constant.

finally, @rate is not set in an instance method, so it is not an instance
variable (think about what self is outside of any instance methode, but inside
a class definition - self == Class)

try

  class Test
    def calc(x)
	return @rate * x
    end
  end

  class Fred < Test
    def initialize
     @rate = 10
    end
  end


  fred = Fred.new
  puts fred.calc 12	>> 120

-a


-- 

 ====================================
 | Ara Howard
 | NOAA Forecast Systems Laboratory
 | Information and Technology Services
 | Data Systems Group
 | R/FST 325 Broadway
 | Boulder, CO 80305-3328
 | Email: ahoward@fsl.noaa.gov
 | Phone:  303-497-7238
 | Fax:    303-497-7259
 ====================================