Neal Becker, 27.08.2010 15:09:
> Stefan Behnel wrote:
>> Neal Becker, 27.08.2010 13:32:
>>> I've noticed that cython extension classes are more restrictive than
>>> boost::python classes. In particular, I believe boost::python allows
>>> attributes to be added by python code to boost::python classes, while
>>> cython
>>> classes are 'closed'. Is this correct?
>>
>> I don't know what kind of classes boost uses, but the above only applies
>> to extension types in Cython. Normal Python classes behave as in normal
>> Python. And it should be possible to add a __dict__ to extension types
>> without much hassle, it's just that most people don't want that.
>> Initialising a dict takes time during type instantiation and takes
>> additional space during the lifetime of the object.
>>
>> BTW, now that you mention it - does anyone know what became of the idea to
>> allow a
>>
>> cdef __dict__
>>
>> attribute notation (as for __weakref__) to add a dict to an extension
>> type? AFAIR, that was already proposed more than once on this list.
>>
>> Stefan
>
> I just tested it. With boost::python you can add attribute to class as well
> as instance of class.
Could you send me the C++ code that it generates for the module?
I checked what CPython does when accessing TheType.__dict__, and it
actually returns a read-only dict proxy:
static PyObject *
type_dict(PyTypeObject *type, void *context)
{
if (type->tp_dict == NULL) {
Py_INCREF(Py_None);
return Py_None;
}
return PyDictProxy_New(type->tp_dict);
}
To work around that, we may have to override the descriptor that returns
the __dict__ through the tp_getset slot of the type.
Stefan
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