[Python-Dev] class dict of subtyped types

[Thomas Heller]

From: "Guido van Rossum" <guido@python.org>
> > C:\>python
> > Python 2.2b1+ (#25, Oct 19 2001, 14:30:05) [MSC 32 bit (Intel)] on win32
> > Type "help", "copyright", "credits" or "license" for more information.
> > >>> class INT(int): pass
> > ...
> > >>> INT.__dict__
> > <dict-proxy object at 0x00769680>
> > >>> INT.__dict__.update
> > Traceback (most recent call last):
> >   File "<stdin>", line 1, in ?
> > AttributeError: 'dict-proxy' object has no attribute 'update'
> > >>> dir(INT.__dict__)
> > ['__class__', '__contains__', '__delattr__', '__getattribute__', '__getitem__', '__hash__'
> > , '__init__', '__iter__', '__len__', '__new__', '__reduce__', '__repr__', '__setattr__', '
> > __str__', 'copy', 'get', 'has_key', 'items', 'keys', 'values']
> > >>>
> > 
> > Other dict attributes are missing as well in the dict-proxy.
> > Is this intentional?
> 
> The dict-proxy type is intended to provide a read-only proxy, so the
> dict-proxy is consciously lacking the update, clear, popitem and
> setdefault methods.  It also seems to be missing the comparison
> operations; that's an oversight.
> 
But adding attributes to the INT class above after creation
is allowed, I hope? At least it currently works.

Thomas