On Fri, Apr 13, 2012 at 9:52 AM, Dag Sverre Seljebotn <d.s.seljeb...@astro.uio.no> wrote: > On 04/13/2012 01:38 AM, Robert Bradshaw wrote: >> Also, I'm not sure the type registration will scale, especially if >> every callable type wanted to get registered. (E.g. currently closures >> and generators are new types...) Where to draw the line? (Perhaps >> things could get registered lazily on the first __nativecall__ lookup, >> as they're likely to be looked up again?) > > > Right... if we do some work to synchronize the types for Cython modules > generated by the same version of Cython, we're left with 3-4 types for > Cython, right? Then a couple for numba and one for f2py; so on the order of > 10? > > An alternative is do something funny in the type object to get across the > offset-in-object information (abusing the docstring, or introduce our own > flag which means that the type object has an additional non-standard field > at the end).
In Python 2.7, it looks like there may be a few TP_FLAG bits free -- 15 and 16 are labeled "reserved for stackless python", and 2, 11, 22 don't have anything defined. There may also be an unused ssize_t field ob_size at the beginning of the type object -- for some reason PyTypeObject is declared as variable size (using PyObject_VAR_HEAD), but I don't see any variable-size fields in it, the docs claim that the ob_size field is a "historical artifact that is maintained for binary compatibility...Always set this field to zero", and Include/object.h has a definition for a PyHeapTypeObject which has a PyTypeObject as its first member, which would not work if PyTypeObject had variable size. Grep says that the only place where ob_type->ob_size is accessed is in Objects/typeobject.c:object_sizeof(), which at first glance appears to be a bug, and anyway I don't think anyone cares whether __sizeof__ on C-callable objects is exactly correct. One could use this for an offset, or even a pointer. One could also add a field easily by just subclassing PyTypeObject. The Signature thing seems like a distraction to me. Signature is intended as just a nice convenient format for looking up stuff that's otherwise stored in more obscure ways -- the API equivalent of pretty-printing. The important thing here is getting the C-level dispatch right. -- Nathaniel _______________________________________________ cython-devel mailing list cython-devel@python.org http://mail.python.org/mailman/listinfo/cython-devel
