From: "jchris@..." <jchris@...>
Date: 2005-11-25T03:27:27+09:00
Subject: Re: syntax error when defining index setter []=

Thanks Yuri,
unfortunately my problems is not as simple. If all I needed was an
array I could write

class T
  attr_accessor :items
  def initialize
    @items = []
  end
end

but what I need is something that acts like an array from outside of
the class, but handles transformations to and from a more complex data
structure "behind the scenes", ie:

class List < ActiveRecord::Base
  has_many :middlemen

  def items
    middlemen.collect {|middleman| middleman.item}
  end

  def items=(new_items)
    new_middlemen = []
    new_items.each do |new_item|
      new_middlemen << Middleman.create :item => new_item
    end
    middlemen = new_middlemen
  end

  def items[]=(index, new_item)  #### this line gives a syntax error
      new_middleman = Middleman.create :item => new_item
      middlemen[index] = new_middleman
  end

end

I could take this to a Rails forum, but it is more of a Ruby question,
as matter of syntax are arising. Running up against this error makes me
think I will come up against more when trying to define items<< etc.

Perhaps better would be to create a dummy object (Array) and have it
run an observer pattern on itself (or something like it). When the
array is changed, it would push those changes through to the middlemen.
Even this is not as clean as I'd like it to be, but maybe there is an
easier way that I'm just not seeing.

Thanks
Chris