[Python-Dev] C-level duck typing

[Dag Sverre Seljebotn]

On 05/16/2012 10:11 AM, Nick Coghlan wrote:
> Use PyObject_HasAttr, just as people use hasattr() for ducktyping in Python.

In the Cython wrap-function-pointers case we really want performance 
comparable to C, so we couldn't do the whole thing.

But I guess we could intern some char* (somehow), pass that to 
tp_getattr, and then cast the returned PyObject* (which would not be a 
PyObject*) to a custom struct. As long as the interned strings can never 
be reached from Python that's almost safe. It's still slight abuse of 
tp_getattr.

As I said, if we didn't worry about performance we'd just retrieve 
capsules through attributes.

Dag


>
> If you want something more structured, use Abstract Base Classes,
> that's what they're for.
>
> Cheers,
> Nick.
>