On 3/29/06, Greg Ewing <[EMAIL PROTECTED]> wrote: > Brett Cannon wrote: > > > Basically a simple > > set interface where we could have a __container__/__view__/__set__ > > whatever method to call to get a view of the data structure. > > Basically a read-only (with a possible delete possibility) mapping > > interface. > > If there's an obvious default meaning for the basic access > methods like __contains__ and __len__, there's no need for > a view to provide these -- the original object can (and > should) just implement them itself. > > Views only come into play when there is more than one > possible view of an object (e.g. dict has keys, items, > values). Then the details are completely type-specific. > > There might be room for a general immutable view object > that doesn't allow any changes, but that could be > provided as a generic wrapper that doesn't need to know > anything about the base object or vice versa. >
Maybe. If people really want to have a frozen set that contains the keys or values of a dict those could be added to the dict type. > > Without a direct reason in terms of the language needing a > > standardization of an interface, perhaps we just don't need > > views. > > On the contrary, views are a very useful idea, *as a > design pattern*. What we *don't* need in Python, as far > as I can see, is any formalised protocols or interfaces > for views, because there's nothing that can be said about > them in general. > > Thinking that "having views" means "having a formally > defined interface for views" is a mindset that comes > from B&D languages like Java. It doesn't apply to > Python at all. > Right. I am just talking about views not being needed in terms of being formalized for the language. Just like how the mapping protocol is there, but not formalized. I am not arguing about the usefulness of views in terms of a concept. -Brett _______________________________________________ Python-3000 mailing list Python-3000@python.org http://mail.python.org/mailman/listinfo/python-3000 Unsubscribe: http://mail.python.org/mailman/options/python-3000/archive%40mail-archive.com
