[Persistence-sig] "Straw Baby" Persistence API

[Steve Menard]

At 10:05 AM 7/22/2002 -0400, Jeremy Hylton wrote:
> >>>>> "GvR" == Guido van Rossum <guido@python.org> writes:
>
>   >> * I do think we should keep PersistentList and PersistentMapping
>   >>   in the
>   >> core; they're useful for almost any kind of application, and any
>   >> kind of back-end storage.  They don't introduce policy or data
>   >> format dependencies into users' code, either.
>
>   GvR> But perhaps these should be rewritten to derive from dict and
>   GvR> list instead of UserDict and UserList?
>
>One small comment.  (I owe more substantial comment on Phillip's
>earlier proposals.)  The persistent versions of dict and list can't
>extend the builtin types, because they need to hook __getitem__() and
>__setitem__().  The overridden methods may not be called if we extend
>the builtin types.
>
>Jeremy

hum, if those method are not guaranteed to be called by subclassing dict or 
list, then there is something broken. Either that or there is a subtle 
thing I do not understand.

On a side note, as I have said in another post, I have done exactly that, 
subclassing dict and list. While my model didn't need to override 
__getitem__(), the __setitem__() at least seemed to act properly. In fact 
the only problem I have found is that it was not possible to mix __slots__ 
and dict/list.

         Steve