On Sat, Jun 30, 2018, 5:59 AM Miro Hrončok <mhroncok@redhat.com> wrote:
During the 3.7 boostrapping of the interstitial sequence of Python 3
packages, I have noticed it includes a lot of packages that are only
intended as Python 3 stdlib backports for older Pythons.

In general, I think this is a good effort however, it's not always straightforward and not always about python3.  There's also at least one item on your list (simplejson) which should remain packaged in Fedora because it is useful as more than forwards compatibility.

Here's an example of how you might need to replace  "import contextlib2":

try:
    import contextlib
except ImportError:
    contextlib = False
else:
     if not hasattr(contextlib, 'nullcontext'):
        contextlib = False
if not contextlib:
    import contextlib2 as contextlib

For each of these libraries and usages you'll have to:

* identify what facilities of the library are being used by the dependent package.
* Figure out if those facilities are present in all versions of the stdlib or not.
* Figure out whether the library in question is truly a backport. I'd be hesitant to replace anything that isn't truly a backport (simplejson definitely shouldn't be treated as a backport, for instance.  mock and unittest2 maybe shouldn't be treated as backports... If all Michael foord for his input)

For the latter, the goal is to identify if there's a reason to use the library for more than just it's API compatibility with newer versions of python 3.  For simplejson, I know that it is faster than the stdlib json library.  It may also have additional API; the stdlib has not pulled the changes from simplejson back into itself (and, iirc, is now best considered a fork of simplejson rather than just a copy).

Also, be careful about how you phrase your requests to upstream to merge your changes.  We don't want to annoy upstreams with requests to use python3 stdlib modules when the backport works just as well for their code for now as too much of that will turn upstream off of python3 altogether.

-Toshio


https://pypi.org/project/contextlib2/ is a backport of the standard
library’s contextlib module to earlier Python versions

https://pypi.org/project/linecache2/ is a backport of linecache to older
supported Pythons.

https://pypi.org/project/pathlib2/ The goal of pathlib2 is to provide a
backport of standard pathlib module which tracks the standard library
module, so all the newest features of the standard pathlib can be used
also on older Python versions.

https://pypi.org/project/traceback2/ is a backport of traceback to older
supported Pythons.

https://pypi.org/project/unittest2/ is a backport of the new features
added to the unittest testing framework in Python 2.7 and onwards.

https://pypi.org/project/simplejson/ is the externally maintained
development version of the json library included with Python 2.6 and
Python 3.0, but maintains backwards compatibility with Python 2.5.

https://pypi.org/project/funcsigs/ is a backport of the PEP 362 function
signature features from Python 3.3

https://pypi.org/project/mock/ is now part of the Python standard
library, available as unittest.mock in Python 3.3 onwards.


Now I see fairly no real reason to have python3-contextlib2,
python3-linecache2 etc. packaged and maintained in Fedora. The only
reason there is that other packages actually depend on them.

I think we should actively change the packages not to depend on those
and eventually get rid of them. This involves changing how upstreams are
using those. Thoughts?


Here is some dependency info:



$ whatrequires python3-contextlib2
python3-futurist
python3-pytest-virtualenv
python3-vcrpy

python-pytest-shutil
python-traceback2



$ whatrequires python3-linecache2
python3-traceback2



$ whatrequires python3-pathlib2
pipenv
python3-spyder

python-testpath



$ whatrequires python3-traceback2
python3-testtools
python3-unittest2



$ whatrequires python3-unittest2
python3-testtools

ProDy
cloud-init
compose-utils
fedpkg
libabigail
pungi
pyephem
python-agate
python-agate-excel
python-autobahn
python-billiard
python-case
python-funcsigs
python-leather
python-linecache2
python-mimerender
python-mock
python-pyclipper
python-pykafka
python-ripozo
python-rsa
python-s3transfer
python-traceback2
python-tw2-core
python-unicodecsv



$ whatrequires python3-simplejson
copr-cli
copr-frontend
copr-rpmbuild
gnome-code-assistance
kismon
python2-pystache (huh?)
python3-canonicaljson
python3-cherrypy
python3-cinderclient
python3-cornice
python3-geojson
python3-jsonpickle
python3-manilaclient
python3-mwclient
python3-neutronclient
python3-novaclient
python3-octaviaclient
python3-osc-lib
python3-oslo-serialization-tests
python3-peewee
python3-rabbitvcs
python3-resultsdb_api
python3-scales
python3-tackerclient
python3-troveclient
python3-tw2-core
python3-tweepy
python3-twitter
python3-uri-templates
python3-x2go
translate-toolkit

pymol
python-anyjson
python-arrow
python-marshmallow
python-mygpoclient
python-openstackclient
python-sphinx



$ whatrequires python3-funcsigs
module-build-service
python3-debtcollector
python3-mock
python3-octaviaclient
python3-oslo-utils
python3-tinyrpc
python3-tinyrpc-tests

odcs
python-ZEO
python-msgpack
python-mwclient
python-ripe-atlas-cousteau


$ whatrequires python3-mock
copr-keygen
module-build-service
python3-ara-tests
python3-certbot
python3-certbot-dns-*
python3-conda
python3-congressclient-tests
python3-keystoneclient-tests
python3-kubernetes-tests
python3-magnumclient-tests
python3-music21
python3-netdiff
python3-octaviaclient-tests
python3-osc-lib-tests
python3-oslo-cache-tests
python3-oslo-log-tests
python3-oslo-middleware-tests
python3-oslo-policy-tests
python3-oslo-rootwrap-tests
python3-oslo-serialization-tests
python3-oslo-service-tests
python3-oslo-versionedobjects
python3-oslo-vmware-tests
python3-oslotest
python3-pytest-spec
python3-pywbem
python3-sphinx
python3-testfixtures-tests
python3-testify
python3-testinfra
python3-tinyrpc-tests
python3-vcrpy
waiverdb

...320 source packages buildrequire this one!

--
Miro Hrončok
--
Phone: +420777974800
IRC: mhroncok
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