On 20110103 13:22, Dirkjan Ochtman wrote:
Do you have actual use cases for these?
On Mon, Jan 3, 2011 at 2:06 PM, K. Richard Pixley <rich@noir.com> wrote:
Yes. Here's a toy example for abstractclassproperty:
Um, a toy example is pretty much the opposite of a use case. :-( That said, I am sure there are use cases for static property and class property -- I've run into them myself. An example use case for class property: in App Engine, we have a Model class (it's similar to Django's Model class). A model has a "kind" which is a string (it's the equivalent of an SQL table name). The kind is usually the class name but sometimes there's a need to override it. However once the class is defined it should be considered read-only. Currently our choices are to make this an instance property (but there are some situations where we don't have an instance, e.g. when creating a new instance using a class method); or to make it a class attribute (but this isn't read-only); or to make it a class method (which requires the user to write M.kind() instead of M.kind). If I had class properties I'd use one here. -- --Guido van Rossum (python.org/~guido)