[Python-Dev] can't set attributes of built-in/extension type

[Guido van Rossum]

On Sat, Feb 23, 2008 at 4:55 PM, Neal Becker <ndbecker2 at gmail.com> wrote:
> There is some discussion on this subject, archived here:
>  http://permalink.gmane.org/gmane.comp.python.general/560661
>
>  I wonder if anyone could shed some light on this subject?
>
>  (Or, help me understand, what is the difference between a type that I create
>  using python C api and a python class?)

This is prohibited intentionally to prevent accidental fatal changes
to built-in types (fatal to parts of the code that you never though
of). Also, it is done to prevent the changes to affect different
interpreters residing in the address space, since built-in types
(unlike user-defined classes) are shared between all such
interpreters.

-- 
--Guido van Rossum (home page: http://www.python.org/~guido/)