Hi Clint, 1) Point taken.
2) The use case can be solved with an object implementing ArrayAccess, but not pragmatically, because then you need a class for *each* bidirectional association. Let me give a short example: Given the class Article with a bidirectional many-to-one relation to Category and a bidirectional many-to-many relation to Tag, currently you implement the following methods to manage these relations: Article::setCategory($category); Article::addTag($tag); Category::addArticle($article); // calls $article->setCategory($category) Tag::addArticle($article); // calls $article->addTag($tag) (there are different ways to implement this, but usually at least one side of the relation also calls the setter/adder on the other side) You *cannot* implement the $articles collection in Category and Tag using the same class ArticleCollection, because in one case addArticle($article) calls setCategory($category), in the other addTag($tag). In other words, ArticleCollection depends both on the related class (Category, Tag) and the arity (setXxx() vs. addXxx()) of the relation. Consequently, every relation needs a custom collection class and you end up with the classes Article Category Tag ArticleTags CategoryArticles TagArticles just for this simple example if following your approach. With array accessors, this can be solved much more elegantly: class Article { public $category { set(); get(); } public $tags { offsetSet(); offsetGet(); } } class Category { public $articles { offsetSet($offset, $article) { $this->_articles[$offset] = $article; $article->category = $this; } offsetGet(); } } class Tag { public $articles { offsetSet($offset, $article) { $this->_articles[$offset] = $article; $article->tags[] = $this; } offsetGet(); } } $article->category = $category; $article->tags[] = $tag; $category->articles[] = $article; // sets $article->category = $category $tag->articles[] = $article; // adds $article->tags[] = $tag (I know that this example has some flaws, like the automatic offsetGet() or the missing $_articles field, but I guess you get my point) 3) I don't know if many other languages allow overloading of the array accessors at all. Cheers, Bernhard -- PHP Internals - PHP Runtime Development Mailing List To unsubscribe, visit: http://www.php.net/unsub.php