In Boost.Python, extension class instance dictionaries are created
only on-demand. It's an obvious win for lots of wrapped C++ class
instances, which will never have Python attributes tacked on. This
also seems like a potential big win for some kinds of Python
instances, like those which use __slots__ but may also have a
dictionary (IIRC that is a possible configuration). The code to do
this in Boost.Python is small and "just works" transparently, so I
thought there might be some interest here for the Python core:
I've "C-ified" the code here, sort of on-the-fly, just to give an
idea, but it's so simple that any errors can't obscure the intent
/too/ much ;-)
static PyObject* instance_get_dict(PyObject* op, void*)
{
bpl_instance* inst = (bpl_instance*)op;
if (inst->dict == 0)
inst->dict = PyDict_New();
Py_XINCREF(inst->dict);
return inst->dict;
}
static int instance_set_dict(PyObject* op, PyObject* dict, void*)
{
(bpl_instance)* inst = (bpl_instance*)op;
Py_XDECREF(inst->dict);
Py_XINCREF(dict);
inst->dict = dict
return 0;
}
static PyGetSetDef instance_getsets[] = { /* used as tp_getset */
{"__dict__", instance_get_dict, instance_set_dict, NULL},
{0}
};
Useful?
-Dave
--
David Abrahams
dave@boost-consulting.com * http://www.boost-consulting.com
Boost support, enhancements, training, and commercial distribution
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