From: "Carlo E. Prelz" <fluido@...>
Date: 2013-02-14T15:27:06+09:00
Subject: Re: Ruby Multithreaded producer-consumer problem

	Subject: Ruby Multithreaded producer-consumer problem
	Date: gio 14 feb 13 12:50:48 +0900

Quoting Abhijit Sarkar (lists@ruby-forum.com):

> 1) The attached code gives me the following exception:
> /Users/Abhijit/Workspace/eclipse/ruby/learn_to_program/orange_tree.rb:84:
> warning: instance variable @orange_tree not initialized
> /Users/Abhijit/Workspace/eclipse/ruby/learn_to_program/orange_tree.rb:84:in
> `<class:Worker>': undefined method `age' for nil:NilClass
> (NoMethodError)
>   from
> /Users/Abhijit/Workspace/eclipse/ruby/learn_to_program/orange_tree.rb:45:in
> `<main>'

Instance variables are only accessible from within methods. Lines
83-86 are not within a method. Take lines 83-86 out of the class
definition, and change them to something like:

worker=Worker.new(Mutex.new,ConditionVariable.new,OrangeTree.new)
worker.do_some_work
until(worker.orange_tree.age==OrangeTree::AGE_TO_DIE)
  # wait for the Threads to finish
end

Of course, variable orange_tree has to be visible from the outside, so
you have to add something like

attr_reader(:orange_tree) 

at the beginning of the Worker class. This way you should not have
those exceptions anymore.

Carlo

-- 
  *         Se la Strada e la sua Virtu' non fossero state messe da parte,
* K * Carlo E. Prelz - fluido@fluido.as             che bisogno ci sarebbe
  *               di parlare tanto di amore e di rettitudine? (Chuang-Tzu)