Some comments on PL/Python documentation

The following documentation comment has been logged on the website:

Page: https://www.postgresql.org/docs/17/plpython-data.html
Description:

Hello,
In my opinion, some phrases on this page are not quite correct.

44.2.4. Composite Types
You say: '...Object (any object providing method __getattr__)...'
Actually, the object class provides the __getattribute__() method but not
the __getattr__() method.
See https://docs.python.org/3/reference/datamodel.html#object.__getattr__

44.2.5. Set-Returning Functions
1. You say: '...Sequence type (tuple, list, set)...'
Being an unordered collection, sets do not record element position or order
of insertion. Accordingly, sets do not support indexing, slicing, or other
sequence-like behavior.
See
https://docs.python.org/3/library/stdtypes.html#set-types-set-frozenset

2. You say: '...Iterator (any object providing __iter__ and next
methods)...'
Actually, the iterator objects must support the __next__() method.
See https://docs.python.org/3/glossary.html#term-iterator

Regards,
Bogdan Grigorenko

On 29.12.24 01:48, PG Doc comments form wrote:
> Page: https://www.postgresql.org/docs/17/plpython-data.html
> Description:
>
> Hello,
> In my opinion, some phrases on this page are not quite correct.
>
> 44.2.4. Composite Types
> You say: '...Object (any object providing method __getattr__)...'
> Actually, the object class provides the __getattribute__() method but not
> the __getattr__() method.
> See https://docs.python.org/3/reference/datamodel.html#object.__getattr__

Yes, this looks slightly inaccurate. I'm not sure __getattribute__ is
fully correct either, because types can also implement other ways of
returning attributes, especially if they are implemented in C. Is there
a neutral and accurate way to describe this?

> 44.2.5. Set-Returning Functions
> 1. You say: '...Sequence type (tuple, list, set)...'
> Being an unordered collection, sets do not record element position or order
> of insertion. Accordingly, sets do not support indexing, slicing, or other
> sequence-like behavior.
> See
> https://docs.python.org/3/library/stdtypes.html#set-types-set-frozenset

I think this is correct as it is. Python sets can be iterated over, so
this works. Note that earlier in the page under composite types it says
"but not a set because it is not indexable", so this distinction was
taken into consideration.

> 2. You say: '...Iterator (any object providing __iter__ and next
> methods)...'
> Actually, the iterator objects must support the __next__() method.
> See https://docs.python.org/3/glossary.html#term-iterator

Yes, this was recently fixed already and will appear in the next patch
release.

On 08.01.25 09:45, Peter Eisentraut wrote:
>> 44.2.5. Set-Returning Functions
>> 1. You say: '...Sequence type (tuple, list, set)...'
>> Being an unordered collection, sets do not record element position or
>> order
>> of insertion. Accordingly, sets do not support indexing, slicing, or
>> other
>> sequence-like behavior.
>> See
>> https://docs.python.org/3/library/stdtypes.html#set-types-set-frozenset
>
> I think this is correct as it is.  Python sets can be iterated over, so
> this works.  Note that earlier in the page under composite types it says
> "but not a set because it is not indexable", so this distinction was
> taken into consideration.

I have added a test for returning Python sets from SETOF functions. It
makes sense to test this if the documentation claims it.