From: Austin Ziegler <austin@...>
Date: 2002-11-09T03:49:17+09:00
Subject: Re: understanding modules/classes

On Sat, 9 Nov 2002 02:53:30 +0900, Eric Schwartz wrote:
> "Gavin Sinclair" <gsinclair@soyabean.com.au> writes:
>> It is perfectly good style to include a module in a class. That
>> is one of the primary aims of modules: in this sense, they are
>> called mix-ins.
> I'm afraid you've confused me further. Let me illustrate.
> 
> module TestHarness
>   class TestTableModel
>     def initialize(project)
>       @project = project
>         # stuff happens
>     end
>     def MachineList
>       # return a list of machines that have test results for the
>       # current project
>     end
>     #... other methods defined, too.
>   end
> end

> This is the Model of an MVC pattern I'm using to display test
> results from a CGI program.
> 
> Now, say I'm writing the CGI itself. Inside it, do I say:

> require 'testharness/testtablemodel'
> require 'testharness/testtableview'
> include TestHarness

IMO, this is what you want. I may prefer to do:

  foo = TestHarness::TestTableModel.new

That is, I might have a TestTableModel in my own code.

I could also choose to do:

  require 'testharness/testtablemodel'

  class Tester
    include TestHarness
    ...
  end

Then Tester has become an alias -- of sorts -- for TestHarness.

module Foo
  class Bar
    def baz
      puts "in Foo::Bar::baz"
    end
  end
end

class Bag
  include Foo
  def initialize
    @bar = Bar.new
  end
  def baz
    puts "in Bag::baz"
    @bar.baz
  end
end

t = Foo::Bar.new
t.baz
  # in Foo::Bar::baz

b = Bag.new
b.baz
  # in Bag::baz
  # in Foo::Bar::baz

z = Bag::Bar.new
z.baz
  # in Foo::Bar::Baz

include Foo
c = Bar.new
c.baz
  # in Foo::Bar::Baz

-austin
-- Austin Ziegler, austin@halostatue.ca on 2002.11.08 at 13.38.27