From: 7stud -- <bbxx789_05ss@...>
Date: 2009-05-04T04:25:23+09:00
Subject: Re: modules and classes question

7stud -- wrote:
>

Another iteration.  Try this:

module Library

  class BaseResource
    @@ready_to_go = false

    def BaseResource.initialize
      puts "initializing"
      @@ready_to_go = true
    end

    def do_stuff
      if not @@ready_to_go
        raise "error"
      else
        puts "doing stuff"
      end
    end

  end

  class SpecializedResource < BaseResource
    def SpecializedResource.meth
      do_stuff
    end
  end

end

Library::BaseResource.initialize
Library::SpecializedResource.meth


That doesn't work.  When you write a method call without an object in 
front of it:

  class SpecializedResource < BaseResource
    def SpecializedResource.meth
      do_stuff    #<-------****
    end
  end

the implicit caller is self.   Inside meth, self is equal to the object 
that called meth.  The object that called meth can be seen in this line:

Library::SpecializedResource.meth

It's the class Library::SpecializedResource.  So inside meth, self is 
equal to the Library::SpecializedResource class.  And the 
Library:SpecializedResource class does not have a method named 
do_stuff--only instances of that class have a method named 
do_stuff(which is inherited from BaseResource).  To call the instance 
method, you need an instance.  So you can do something like this:

 class SpecializedResource < BaseResource
    def SpecializedResource.meth
      sr = SpecializedResource.new
      sr.do_stuff
    end
  end



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