[Python-Dev] Extending types in C (original) (raw)

[Python-Dev] Extending types in C - help needed

Jack Jansen Jack.Jansen@oratrix.nl
Thu, 7 Feb 2002 23:43:46 +0100

On Wednesday, February 6, 2002, at 09:53 PM, Thomas Heller wrote:

A better solution is to store additional information in the dict. You loose nice features: access these (new) slots from Python by providing tpmembers entries for them (for example).

Martin pointed at a way to solve this. And I think that with my proposed API (... where is it..., ah yes, found it) void PyType_SetAnnotation(PyTypeObject *tp, char *name, void *unique, void *); void *PyType_GetAnnotation(PyTypeObject *tp, char *name, void *unique);

it would be almost as easy to use as a tp_ slot. The only thing needed to make it 100% safe is a registry for name/descr pairs. (Actually the API is changed a little since I understand how the second arg works)

For the benefit of whoever missed the previous thread: name is used as the key into the dictionary, and unique is a pointer stored with the entry, which assures that this entry hasn't been used for something else accidentally.

So in stead of a new slot tp_foo what you would need to do is come up with a name ("tp_foo" comes to mind) and a global variable whose address can be used for unique.