Support for Python 3.10 w suggested fix

[luss]

Hey my friend,

thanks so much for creating the economy of Postgres extensions.

Im getting an error when using Postgresql 14 and Python 3.10. After my fix it worked. When I load the extension:

    CREATE EXTENSION multicorn;

I get this error:

 2022-05-09 18:58:49.386 CEST [7957] DETAIL:  Traceback (most recent

call last):

 File

"/usr/lib/python3.10/site-packages/multicorn-2.2-py3.10-linux-x86_64.egg/multicorn/init.py", line 543, in get_class module = import_module(module_name)

 File

"/usr/lib/python3.10/site-packages/multicorn-2.2-py3.10-linux-x86_64.egg/multicorn/init.py", line 523, in import_module import(name)

 File

"/usr/lib/python3.10/site-packages/multicorn-2.2-py3.10-linux-x86_64.egg/multicorn/fsfdw/init.py", line 109, in from multicorn.fsfdw.structuredfs import StructuredDirectory

 File

"/usr/lib/python3.10/site-packages/multicorn-2.2-py3.10-linux-x86_64.egg/multicorn/fsfdw/structuredfs.py", line 169, in class Item(collections.Mapping):

 AttributeError: module 'collections' has no attribute 'Mapping'

 2022-05-09 18:58:49.386 CEST [7957] ANWEISUNG:  CREATE EXTENSION

multicorn;

The fix (makes multicorn2 incompatible with Python 2): In multicorn2/python/multicorn/fsfdw/structuredfs.py change the import of collections to collections.abc and the inheritance of class Item(collections.Mapping) to (collections.abc.Mapping)

 import collections.abc
 ...
 class Item(collections.abc.Mapping):
 ...

It would also be possible to do the following fix instead to ensure compatibility with Python 2. That introduces the dependency six. But that fix faulted with ImportError: cannot import name 'colletions_abc' from 'six.moves' (unknown location) on my setup.

 from six.moves import collections_abc
 ...
 class Item(collections_abc.Mapping):
 ...

Sorry for not writing a pull request. Github is too extemely annyoing to use as a mammal. I created a new account on Github but it got instantly banned from public. Even my issue is not visible publicly. Maybe you could host repos on git.pgsql.io haha.

<3333333 Best f

[luss]

I will look into applying this in the near future for version 2.3. Since Multicorn2 is only purporting to work with Python 3.6+, I'll opt to keep-it-simple and not introduce a dependency on six.

[luss]

I checked in the suggested fix, but, haven't tested it yet.

[luss]

it works