On 2008-11-21 19:36, Adam Olsen wrote:
> On Fri, Nov 21, 2008 at 10:53 AM, M.-A. Lemburg <[EMAIL PROTECTED]> wrote:
>> Yes, it's a different way of writing and accessing the resp. fields.
>> No, it's not a different memory layout.
>> Yes, this is binary compatible.
>> No, this is not going to help you, since the rest of Python 3 is not ;-)
>
> You're comparing already compiled code. The issue is with
> recompiling, ie source compatibility.
>
> In 2.5 the macros expanded to look like this:
>
> PyTypeObject PyUnicode_Type = {
> 1, /* ob_refcnt */
> &PyType_Type, /* ob_type */
> 0, /* ob_size */
> "unicode", /* tp_name */
> sizeof(PyUnicodeObject), /* tp_basicsize */
>
> Try the same macro in 3.0 and it'll look like this:
>
> PyTypeObject PyUnicode_Type = {
> {
> {
> 1, /* ob_refcnt */
> &PyType_Type, /* ob_type */
> },
> /* Trailing ob_size gets implicitly initialized to 0 */
> },
> 0, /* ob_size? Nope, tp_name! */
> "unicode", /* tp_name? Nope, tp_basicsize! */
> sizeof(PyUnicodeObject), /* tp_basicsize? Nope, tp_itemsize!
> */
>
> The compiler knows what layout a PyTypeObject should have, but the
> initializer doesn't match up.
Well, yes, of course. That's the whole purpose of PEP 3123, isn't it ?
Starting with Python 3, you have to use PyVarObject_HEAD_INIT()
on PyVarObjects and PyObject_HEAD_INIT() on PyObjects. I don't
see the problem. It's just another change to remember when porting
to Python 3.
The whole type slot interface has changed significantly between
Python 2 and 3, so this minor clarification is really harmless compared
to all the other changes:
* PyNumberMethods have changed due to removal of the division,
oct, hex and coercion slots
* PySequenceMethods have changed, but maintained binary compatibility
(why ?) by replacing the removed slice functions with dummy pointers
* PyBufferProcs is a completely new design
* A lot type flags were removed.
--
Marc-Andre Lemburg
eGenix.com
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