> > One last point. While I remain interested in examples of how > "late" addition of attributes to class instances is useful, > I must note that everyone who responded agreed that it > has been a source of bugs. This seems to argue against a > general ban on "locking" objects in some way, in some > circumstances.
I've got some examples. I quite often used dynamic attributes in situations where I wasn't the creator of certain objects, but had to use them and wanted to link them with my own code. For example, in various GUI-environments, you've got some sort of tree view, usually containing item-objects that form the tree. Now in other languages like C++ or Java, I have to subclass those items (if possible at all) if I want to associate my own data (for example the "real" object behind such an item) with them. Or I need to have an awkward global mapping between tree-items and my data. But in python, I can just easily add a new .data_object property, and in whatever event-handler spits a e.g. selected item at me, I'm easily accessing the data behind it. Other examples are processing XML-trees that also have associated data and the like. Diez -- http://mail.python.org/mailman/listinfo/python-list
