Обсуждение: PL/Python result set slicing broken in Python 3
This doesn't work anymore with Python 3: rv = plpy.execute(...) do_something(rv[0:1]) Apparently, they changed the C API for doing slicing, or rather made one of the two APIs for it silently do nothing. Details are difficult to find, but this email message seems to contain something: <http://mail.python.org/pipermail/python-3000/2007-August/009851.html>. I'll try to sort this out sometime, but if someone wants to take a shot at it, go ahead.
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]) > > Apparently, they changed the C API for doing slicing, or rather made one > of the two APIs for it silently do nothing. Details are difficult to > find, but this email message seems to contain something: > <http://mail.python.org/pipermail/python-3000/2007-August/009851.html>. > > I'll try to sort this out sometime, but if someone wants to take a shot > at it, go ahead. Sounds ugly. I'll take a look. Cheers, Jan
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]) >> >> Apparently, they changed the C API for doing slicing, or rather made one >> of the two APIs for it silently do nothing. Details are difficult to >> find, but this email message seems to contain something: >> <http://mail.python.org/pipermail/python-3000/2007-August/009851.html>. >> >> I'll try to sort this out sometime, but if someone wants to take a shot >> at it, go ahead. > > 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 Apparently you need that egregious hack in order to avoid code duplication. I'll try to produce a patch over the weekend. Cheers, Jan
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
Вложения
On Sat, May 5, 2012 at 4:45 PM, Jan Urbański <wulczer@wulczer.org> wrote: >> 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. Did this get forgotten about? -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company
On tor, 2012-05-10 at 12:37 -0400, Robert Haas wrote: > On Sat, May 5, 2012 at 4:45 PM, Jan Urbański <wulczer@wulczer.org> wrote: > >> 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. > > Did this get forgotten about? I'm working on it.
On lör, 2012-05-05 at 22:45 +0200, Jan Urbański wrote: > 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). Committed this now. From test coverage reports, I now see that PLy_result_ass_item() is no longer called. That's probably OK, if assignments are now handled through the mapping methods. But should we remove the function then? > > 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. I don't think this should be backpatched.
On 10/05/12 19:45, Peter Eisentraut wrote: > On lör, 2012-05-05 at 22:45 +0200, Jan Urbański wrote: >> 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). > > Committed this now. > > From test coverage reports, I now see that PLy_result_ass_item() is no > longer called. That's probably OK, if assignments are now handled > through the mapping methods. But should we remove the function then? Have you tried on Python 2.3 as well? People on #python said that if you implement the mapping functions, the sequence slicing functions are no longer used, but maybe we should revisit for the next release, rather than risk introducing a regression for the benefit of removing a few dead lines. Cheers, Jan
On fre, 2012-05-11 at 11:28 +0200, Jan Urbański wrote: > On 10/05/12 19:45, Peter Eisentraut wrote: > > On lör, 2012-05-05 at 22:45 +0200, Jan Urbański wrote: > >> 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). > > > > Committed this now. > > > > From test coverage reports, I now see that PLy_result_ass_item() is no > > longer called. That's probably OK, if assignments are now handled > > through the mapping methods. But should we remove the function then? > > Have you tried on Python 2.3 as well? People on #python said that if you > implement the mapping functions, the sequence slicing functions are no > longer used, but maybe we should revisit for the next release, rather > than risk introducing a regression for the benefit of removing a few > dead lines. I did test Python 2.3, but you're right, we should leave this alone during beta.