From: Robert Klemme <shortcutter@...>
Date: 2006-08-12T22:50:08+09:00
Subject: Re: Modules -> do I have is straight?

Carl Jenkins <carljenkins@gmail.com> wrote:
> I was hoping I could expand on the thread a little bit...
>
> I sort of understand modules, according to what I have read in my
> fancy ruby book and this forum modules are like superclasses. But,
> what about this < ?
> Doesn't this allow a class to "become" a subclass of another by way of
> inheritance. Not sure I am catching the difference between the two.

class Base
end

class Descendant < Base
end

Descendant is a subclass of Base.

module Foo
end

class Bar
  include Foo
end

Foo is mixed into Bar.  You can combine both approaches.

class Deri2 < Base
  include Foo
end

Deri2 inherits Base and mixes in Foo.  You can use instance methods from 
Base and Foo in Deri2.

> Also, I am not quite sure I understand how namespaces works in ruby.
> In java you create a package ( i know you all know this already I am
> just saying it for my benefit) to place related classes in. Say for
> example com.jenkins.util.MyFancyClass. If I want to use this class in
> another package com.jenkins.library any classs in library would just
> import it. How does this work in ruby?

module com
  module jenkins
    module util
      class MyFancyClass
      end
    end
  end
end

Now you have

com::jenkins::util::MyClass

Or you do

include com::jenkins::util
MyClass

> Most of the code I have seen is in the same class or at least the same
> direcctory. Is it typical for ruby applications to create a package
> structure similar to a java app?

You can do that. From what I've seen though these hiearchies are not as deep 
as they are usually in Java.

Kind regards

    robert