On Fri, Jun 10, 2011 at 11:26 AM, Ian Kelly <ian.g.ke...@gmail.com> wrote: > Everybody always focuses so much on properties and forgets that you > can also just write your own descriptors. >
I'm so glad that you pointed this out. I totally forgot that properties simply returned themselves if not called on the instance. You are right about a custom descriptor. -eric >>>> class DocDescriptor(object): > ... def __get__(self, instance, owner): > ... return getattr(owner, "_mydoc", None) > ... >>>> class Meta(type): > ... def __init__(cls, name, bases, d): > ... super(Meta, cls).__init__(name, bases, d) > ... cls.__doc__ = DocDescriptor() > ... >>>> class X(object): > ... __metaclass__ = Meta > ... >>>> X.__doc__ >>>> X().__doc__ >>>> X._mydoc = 'test' >>>> X.__doc__ > 'test' >>>> X().__doc__ > 'test' >>>> class Derived(X): pass > ... >>>> Derived.__doc__ > 'test' >>>> Derived().__doc__ > 'test' > > There you go, a metaclass that adds a __doc__ descriptor that can be > inherited (thanks to the metaclass), can be accessed from either the > class or the instance (thanks to the descriptor), and can easily be > modified to generate the doc string dynamically at call-time if > desired. > > Cheers, > Ian > -- http://mail.python.org/mailman/listinfo/python-list
