From: jlr8 <jonathan.ruckwood@...>
Date: 2005-11-26T02:47:28+09:00
Subject: Newbie Mixin Problem

Hi, I'm new to Ruby and have done some reading on it. To learn more
about it I'm attempting to re-write some of my Java code. However I
have run into a problem with Modules/Mixins that I can't seem to solve.
My problem is like this; I have a module with the instance method
validIndex? (and some constants) which is included into my other
classes; Board, Strategy and Player.

module Common

  MAX_ENTRIES = 19682

  def validIndex?(index)
    if index >= 0 && index <= MAX_ENTRIES then
      return true
    else
      return false
    end
  end
end

Each Player has two Strategies and Boards represent these. When
creating a Board instance I can use validIndex?, however when creating
a Strategy or Player (which creates new Boards) I get:

NoMethodError: undefined method `validIndex?' for Board:Class
        from /Users/jon_r/Projects/RbNoughtsCrosses/Board.rb:31:in
`numToBoard'
        from /Users/jon_r/Projects/RbNoughtsCrosses/Strategy.rb:13:in
`initialize'
        from /Users/jon_r/Projects/RbNoughtsCrosses/Strategy.rb:12:in
`each'
        from /Users/jon_r/Projects/RbNoughtsCrosses/Strategy.rb:12:in
`initialize'
        from /Users/jon_r/Projects/RbNoughtsCrosses/Player.rb:15:in
`new'
        from /Users/jon_r/Projects/RbNoughtsCrosses/Player.rb:15:in
`initialize'
        from (irb):5:in `new'
        from (irb):5

But when I check each classes instance methods I see validIndex?
listed. I'm confused, as in my eyes, it's similar to the who_am_i?
example given in the book. However there is still a lot for me to
learn. Does anybody recognise this situation, or where I'm going wrong?
I'm sorry if it's stupid but I have tried to find solutions from other
sources. Cheers.

Jonathan