Re: PL/Python result set slicing broken in Python 3

Jan Urbański <wulczer@wulczer.org>

From: Jan Urbański <wulczer@wulczer.org>
To: Peter Eisentraut <peter_e@gmx.net>
Cc: pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2012-05-05T20:45:15Z
Lists: pgsql-hackers

Attachments

On 04/05/12 20:00, Jan Urbański wrote:
> On 03/05/12 11:04, Jan Urbański wrote:
>> On 02/05/12 20:18, Peter Eisentraut wrote:
>>> This doesn't work anymore with Python 3:
>>>
>>> rv = plpy.execute(...)
>>> do_something(rv[0:1])
>>>
>> Sounds ugly. I'll take a look.
>
> I found some instructions on how to deal with the Python 2/Python 3
> slicing mess:
>
> http://renesd.blogspot.com/2009/07/python3-c-api-simple-slicing-sqslice.html

Thanks to the helpful folk at #python I found out that the fix is much 
easier. Attached is a patch that fixes the bug and passes regression 
tests on Pythons 2.3 through 3.2.

Apparently once you implement PyMappingMethods.mp_subscript you can drop 
PySequenceMethods.sq_slice, but I guess there's no harm in keeping it 
(and I'm not sure it'd work on Python 2.3 with only mp_subscript 
implemented).

Do we want to backpatch this? If so, I'd need to produce a version that 
applies to the monolithic plpython.c file from the previous releases.

Cheers,
Jan