gistfile1.coffee

App.BookIndexController = Ember.ArrayController.extend
  content: []           # array of books
  proxies: {}           # proxy cache for books

  # Creates and caches a proxy that will wrap around our book
  createProxy: (book, id) ->
    @proxies[id] = BookProxy.create
      content: book
      controller: this

  # This wraps each book in our book array w/ a proxy
  objectAtContent: (index) ->
    book = @get('arrangedContent').objectAt(index)
    if book?
      book_id = book.get('id')
      if @proxies[book_id] then @proxies[book_id] else @createProxy(book,book_id)

BookProxy = Em.ObjectProxy.extend
  isSelected: (->
    @get('controller.selectedBook') == @get('content')
  ).property('controller.selectedBook')
  # Other stuff goes here for augmenting the book model / behavior