[Python-3000] Type parameterization

[Jim Jewett]

On 5/19/06, Marcin 'Qrczak' Kowalczyk <qrczak at knm.org.pl> wrote:
> "Jim Jewett" <jimjjewett at gmail.com> writes:
>
> > __getitem__ on a dictionary instance happens to be defined.
> > __getitem__ on the dict class happens not to be defined.
>
> I wouldn't be so sure.
>
> >>> dict.__getitem__
> <method '__getitem__' of 'dict' objects>
> >>> dict.__getitem__({'one':1}, 'one')
> 1

I should have been more precise.

On a dictionary instance, __getitem__ wil be found (in the definition
of the class dict)

On a type instance, such as dict itself, __getitem__ will not be found
(in the definition of the (meta)class type)

If the implementation of [] ends up doing the moral equivalent of

    (self.__getitem__(arg) if not isintance(self, type) else
self.__parameterization__(arg))

then we're running into problems with

    If the implementation is hard to explain, it's a bad idea.

-jJ