[Python-Dev] On C inheritance

Christian Tismer tismer@tismer.com
Sun, 04 Aug 2002 14:01:47 +0200

Hi Guido,

as you know, I love your new type/class implementation very
much as it is right now, probably not completely ready, but
performing great.
Yesterday, at the Berlin Python Community Meeting, we were
discussing several aspects of this.
A special issue was overloading of methods from C.
With the current design, it appears to be "correct" to call my
own methods always vial the dictionary interface of the type,
since users might have derived from it and want their versions
to be called.

Now, this is a performance issue, and there are of course special
cased things like "getattr" already, which make use of an extra slot
in the type structure to speed it up.

Now, all my new stackless objects are made inheritable from, and
I'd like to support it from C code as well, but I hesitate to
spend the extra dictionary lookup for a probably seldom case.
Therefore, I intended to extend my types in a way, that they
provide some extra type slots for overridden builtin methods.

Unfortunately, this is not supported at the moment, due to some
extension class compatibility issues. I'd like to patch this,
and allow metatypes to be extzended with extra function fields.

Would you support this? Or is something already on your boiler plate?

thanks - chris
Christian Tismer             :^)   <mailto:tismer@tismer.com>
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