[Python-Dev] Exception for setting attributes of built-in type (original) (raw)

Guido van Rossum guido at python.org
Mon Jun 15 16:48:33 CEST 2009

On Sun, Jun 14, 2009 at 4:19 PM, Guido van Rossum<guido at python.org> wrote:

In general, CPython isn't always consistent in raising AttributeError and TypeError when it comes to such policy issues: there are various places that raise TypeError in typeobject.c (and probably elsewhere) that simply forbid setting a specific attribute (another example is name).

I should add that this policy is also forced somewhat by the existence of the "multiple interpreters in one address space" feature, which is used e.g. by mod_python. This feature attempts to provide isolation between interpreters to the point that each one can have a completely different set of modules loaded and can be working on a totally different application. The implementation of CPython shares built-in types between multiple interpreters (and it wouldn't be easy to change this); if you were able to modify a built-in type from one interpreter, all other interpreters would see that same modification.

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

More information about the Python-Dev mailing list