Making enum34 dependency conditional on Python version.

[dhermes]

Fixes#3398.

---

After using this and running the unit tests, the dependency is indeed only present in Python 2.7:

$ .nox/unit_tests-python_version-2-7/bin/pip freeze > 27.txt
$ .nox/unit_tests-python_version-3-4/bin/pip freeze > 34.txt
$ .nox/unit_tests-python_version-3-5/bin/pip freeze > 35.txt
$ .nox/unit_tests-python_version-3-6/bin/pip freeze > 36.txt
$
$ diff -s 34.txt 35.txt
Files 34.txt and 35.txt are identical
$ diff -s 34.txt 36.txt
Files 34.txt and 36.txt are identical
$
$ diff -s 27.txt 34.txt
--- 27.txt 2017-05-11 10:28:41.369890164 -0700
+++ 34.txt 2017-05-11 10:28:36.081426963 -0700
@@ -2,10 +2,7 @@
cachetools==2.0.0
coverage==4.4
dill==0.2.6
-enum34==1.1.6
-funcsigs==1.0.2
future==0.16.0
-futures==3.1.1
gapic-google-cloud-vision-v1==0.90.3
google-auth==1.0.1
google-auth-httplib2==0.0.2

[tseaver]

I don't mind the change, but I'd really like to know how our code appears to work on Python 3.6 without this change.

[theacodes]

So it seems package metadata (and therefore wheels) do not store the platform qualifiers, so installing from wheel in python 3 will cause enum34 to be installed. I had a fear that this would be the case:

pip install google_cloud_vision-0.24.0-py2.py3-none-any.whl
Processing ./google_cloud_vision-0.24.0-py2.py3-none-any.whl
Collecting gapic-google-cloud-vision-v1<0.91dev,>=0.90.3 (from google-cloud-vision==0.24.0)
Using cached gapic-google-cloud-vision-v1-0.90.3.tar.gz
Collecting enum34 (from google-cloud-vision==0.24.0)
Using cached enum34-1.1.6-py3-none-any.whl
Collecting google-cloud-core<0.25dev,>=0.24.0 (from google-cloud-vision==0.24.0)
Using cached google_cloud_core-0.24.1-py2.py3-none-any.whl
Collecting google-gax<0.16dev,>=0.15.7 (from gapic-google-cloud-vision-v1<0.91dev,>=0.90.3->google-cloud-vision==0.24.0)
Collecting oauth2client<4.0dev,>=2.0.0 (from gapic-google-cloud-vision-v1<0.91dev,>=0.90.3->google-cloud-vision==0.24.0)
Collecting proto-google-cloud-vision-v1[grpc]<0.91dev,>=0.90.3 (from gapic-google-cloud-vision-v1<0.91dev,>=0.90.3->google-cloud-vision==0.24.0)
Using cached proto-google-cloud-vision-v1-0.90.3.tar.gz
Collecting googleapis-common-protos[grpc]<2.0dev,>=1.5.2 (from gapic-google-cloud-vision-v1<0.91dev,>=0.90.3->google-cloud-vision==0.24.0)
Collecting httplib2>=0.9.1 (from google-cloud-core<0.25dev,>=0.24.0->google-cloud-vision==0.24.0)
Collecting protobuf>=3.0.0 (from google-cloud-core<0.25dev,>=0.24.0->google-cloud-vision==0.24.0)
Collecting google-auth<2.0.0dev,>=0.4.0 (from google-cloud-core<0.25dev,>=0.24.0->google-cloud-vision==0.24.0)
Using cached google_auth-1.0.1-py2.py3-none-any.whl
Collecting google-auth-httplib2 (from google-cloud-core<0.25dev,>=0.24.0->google-cloud-vision==0.24.0)
Using cached google_auth_httplib2-0.0.2-py2.py3-none-any.whl
Requirement already satisfied: six in /private/tmp/env/lib/python3.6/site-packages (from google-cloud-core<0.25dev,>=0.24.0->google-cloud-vision==0.24.0)
Collecting requests<3.0dev,>=2.13.0 (from google-gax<0.16dev,>=0.15.7->gapic-google-cloud-vision-v1<0.91dev,>=0.90.3->google-cloud-vision==0.24.0)
Using cached requests-2.14.2-py2.py3-none-any.whl
Collecting future<0.17dev,>=0.16.0 (from google-gax<0.16dev,>=0.15.7->gapic-google-cloud-vision-v1<0.91dev,>=0.90.3->google-cloud-vision==0.24.0)
Collecting dill<0.3dev,>=0.2.5 (from google-gax<0.16dev,>=0.15.7->gapic-google-cloud-vision-v1<0.91dev,>=0.90.3->google-cloud-vision==0.24.0)
Collecting ply==3.8 (from google-gax<0.16dev,>=0.15.7->gapic-google-cloud-vision-v1<0.91dev,>=0.90.3->google-cloud-vision==0.24.0)
Collecting grpcio<2.0dev,>=1.0.2 (from google-gax<0.16dev,>=0.15.7->gapic-google-cloud-vision-v1<0.91dev,>=0.90.3->google-cloud-vision==0.24.0)
Using cached grpcio-1.3.0-cp36-cp36m-macosx_10_7_intel.whl
Collecting pyasn1-modules>=0.0.5 (from oauth2client<4.0dev,>=2.0.0->gapic-google-cloud-vision-v1<0.91dev,>=0.90.3->google-cloud-vision==0.24.0)
Using cached pyasn1_modules-0.0.8-py2.py3-none-any.whl
Collecting pyasn1>=0.1.7 (from oauth2client<4.0dev,>=2.0.0->gapic-google-cloud-vision-v1<0.91dev,>=0.90.3->google-cloud-vision==0.24.0)
Using cached pyasn1-0.2.3-py2.py3-none-any.whl
Collecting rsa>=3.1.4 (from oauth2client<4.0dev,>=2.0.0->gapic-google-cloud-vision-v1<0.91dev,>=0.90.3->google-cloud-vision==0.24.0)
Using cached rsa-3.4.2-py2.py3-none-any.whl
Requirement already satisfied: setuptools in /private/tmp/env/lib/python3.6/site-packages (from protobuf>=3.0.0->google-cloud-core<0.25dev,>=0.24.0->google-cloud-vision==0.24.0)
Collecting cachetools>=2.0.0 (from google-auth<2.0.0dev,>=0.4.0->google-cloud-core<0.25dev,>=0.24.0->google-cloud-vision==0.24.0)
Using cached cachetools-2.0.0-py2.py3-none-any.whl
Requirement already satisfied: appdirs>=1.4.0 in /private/tmp/env/lib/python3.6/site-packages (from setuptools->protobuf>=3.0.0->google-cloud-core<0.25dev,>=0.24.0->google-cloud-vision==0.24.0)
Requirement already satisfied: packaging>=16.8 in /private/tmp/env/lib/python3.6/site-packages (from setuptools->protobuf>=3.0.0->google-cloud-core<0.25dev,>=0.24.0->google-cloud-vision==0.24.0)
Requirement already satisfied: pyparsing in /private/tmp/env/lib/python3.6/site-packages (from packaging>=16.8->setuptools->protobuf>=3.0.0->google-cloud-core<0.25dev,>=0.24.0->google-cloud-vision==0.24.0)
Building wheels for collected packages: gapic-google-cloud-vision-v1, proto-google-cloud-vision-v1
Running setup.py bdist_wheel for gapic-google-cloud-vision-v1 ... done
Stored in directory: /Users/jonwayne/Library/Caches/pip/wheels/ce/0f/77/6ac253c303b8a0b4b985796f618f62ffaf0c1bb82e86b7b27f
Running setup.py bdist_wheel for proto-google-cloud-vision-v1 ... done
Stored in directory: /Users/jonwayne/Library/Caches/pip/wheels/cc/39/4f/ba1cc41634e5a468627c7194093313e268f69432c8f9ae7fa2
Successfully built gapic-google-cloud-vision-v1 proto-google-cloud-vision-v1
Installing collected packages: requests, protobuf, future, grpcio, googleapis-common-protos, pyasn1, pyasn1-modules, cachetools, rsa, google-auth, dill, ply, google-gax, httplib2, oauth2client, proto-google-cloud-vision-v1, gapic-google-cloud-vision-v1, enum34, google-auth-httplib2, google-cloud-core, google-cloud-vision
Successfully installed cachetools-2.0.0 dill-0.2.6 enum34-1.1.6 future-0.16.0 gapic-google-cloud-vision-v1-0.90.3 google-auth-1.0.1 google-auth-httplib2-0.0.2 google-cloud-core-0.24.1 google-cloud-vision-0.24.0 google-gax-0.15.12 googleapis-common-protos-1.5.2 grpcio-1.3.0 httplib2-0.10.3 oauth2client-3.0.0 ply-3.8 proto-google-cloud-vision-v1-0.90.3 protobuf-3.3.0 pyasn1-0.2.3 pyasn1-modules-0.0.8 requests-2.14.2 rsa-3.4.2

[dhermes]

@jonparrott Shucks / thanks for bringing your packaging magic to bear here. What can we do?

[dhermes]

@tseaver Regarding "how our code appears to work", see my response on the bug report.

[theacodes]

We can do it via extras_require as noted in the wheel docs:

extras_require={
':python_version<"3.4"': ['enum34'],
}

This explodes with setuptools<18 (ref), but that was released in 2015, so I think we're safe.

[dhermes]

PR updated. Thanks a lot @jonparrott! I did the same pip freeze verification with this new setup and the diffs were exactly as before.

[theacodes]

Confirmed wheel installation skips enum34 on Python 3.6:

Processing ./google_cloud_vision-0.24.0-py2.py3-none-any.whl
Collecting google-cloud-core<0.25dev,>=0.24.0 (from google-cloud-vision==0.24.0)
Using cached google_cloud_core-0.24.1-py2.py3-none-any.whl
Collecting gapic-google-cloud-vision-v1<0.91dev,>=0.90.3 (from google-cloud-vision==0.24.0)
Collecting googleapis-common-protos>=1.3.4 (from google-cloud-core<0.25dev,>=0.24.0->google-cloud-vision==0.24.0)
Collecting httplib2>=0.9.1 (from google-cloud-core<0.25dev,>=0.24.0->google-cloud-vision==0.24.0)
Collecting google-auth-httplib2 (from google-cloud-core<0.25dev,>=0.24.0->google-cloud-vision==0.24.0)
Using cached google_auth_httplib2-0.0.2-py2.py3-none-any.whl
Requirement already satisfied: six in /private/tmp/env/lib/python3.6/site-packages (from google-cloud-core<0.25dev,>=0.24.0->google-cloud-vision==0.24.0)
Collecting google-auth<2.0.0dev,>=0.4.0 (from google-cloud-core<0.25dev,>=0.24.0->google-cloud-vision==0.24.0)
Using cached google_auth-1.0.1-py2.py3-none-any.whl
Collecting protobuf>=3.0.0 (from google-cloud-core<0.25dev,>=0.24.0->google-cloud-vision==0.24.0)
Collecting proto-google-cloud-vision-v1[grpc]<0.91dev,>=0.90.3 (from gapic-google-cloud-vision-v1<0.91dev,>=0.90.3->google-cloud-vision==0.24.0)
Collecting google-gax<0.16dev,>=0.15.7 (from gapic-google-cloud-vision-v1<0.91dev,>=0.90.3->google-cloud-vision==0.24.0)
Collecting oauth2client<4.0dev,>=2.0.0 (from gapic-google-cloud-vision-v1<0.91dev,>=0.90.3->google-cloud-vision==0.24.0)
Collecting pyasn1>=0.1.7 (from google-auth-httplib2->google-cloud-core<0.25dev,>=0.24.0->google-cloud-vision==0.24.0)
Using cached pyasn1-0.2.3-py2.py3-none-any.whl
Collecting pyasn1-modules>=0.0.5 (from google-auth-httplib2->google-cloud-core<0.25dev,>=0.24.0->google-cloud-vision==0.24.0)
Using cached pyasn1_modules-0.0.8-py2.py3-none-any.whl
Collecting rsa>=3.1.4 (from google-auth-httplib2->google-cloud-core<0.25dev,>=0.24.0->google-cloud-vision==0.24.0)
Using cached rsa-3.4.2-py2.py3-none-any.whl
Collecting cachetools>=2.0.0 (from google-auth<2.0.0dev,>=0.4.0->google-cloud-core<0.25dev,>=0.24.0->google-cloud-vision==0.24.0)
Using cached cachetools-2.0.0-py2.py3-none-any.whl
Requirement already satisfied: setuptools in /private/tmp/env/lib/python3.6/site-packages (from protobuf>=3.0.0->google-cloud-core<0.25dev,>=0.24.0->google-cloud-vision==0.24.0)
Collecting grpcio<2.0dev,>=1.0.2; extra == "grpc" (from proto-google-cloud-vision-v1[grpc]<0.91dev,>=0.90.3->gapic-google-cloud-vision-v1<0.91dev,>=0.90.3->google-cloud-vision==0.24.0)
Using cached grpcio-1.3.0-cp36-cp36m-macosx_10_7_intel.whl
Collecting dill<0.3dev,>=0.2.5 (from google-gax<0.16dev,>=0.15.7->gapic-google-cloud-vision-v1<0.91dev,>=0.90.3->google-cloud-vision==0.24.0)
Collecting requests<3.0dev,>=2.13.0 (from google-gax<0.16dev,>=0.15.7->gapic-google-cloud-vision-v1<0.91dev,>=0.90.3->google-cloud-vision==0.24.0)
Using cached requests-2.14.2-py2.py3-none-any.whl
Collecting ply==3.8 (from google-gax<0.16dev,>=0.15.7->gapic-google-cloud-vision-v1<0.91dev,>=0.90.3->google-cloud-vision==0.24.0)
Collecting future<0.17dev,>=0.16.0 (from google-gax<0.16dev,>=0.15.7->gapic-google-cloud-vision-v1<0.91dev,>=0.90.3->google-cloud-vision==0.24.0)
Requirement already satisfied: appdirs>=1.4.0 in /private/tmp/env/lib/python3.6/site-packages (from setuptools->protobuf>=3.0.0->google-cloud-core<0.25dev,>=0.24.0->google-cloud-vision==0.24.0)
Requirement already satisfied: packaging>=16.8 in /private/tmp/env/lib/python3.6/site-packages (from setuptools->protobuf>=3.0.0->google-cloud-core<0.25dev,>=0.24.0->google-cloud-vision==0.24.0)
Requirement already satisfied: pyparsing in /private/tmp/env/lib/python3.6/site-packages (from packaging>=16.8->setuptools->protobuf>=3.0.0->google-cloud-core<0.25dev,>=0.24.0->google-cloud-vision==0.24.0)
Installing collected packages: protobuf, googleapis-common-protos, httplib2, pyasn1, cachetools, pyasn1-modules, rsa, google-auth, google-auth-httplib2, google-cloud-core, oauth2client, grpcio, proto-google-cloud-vision-v1, dill, requests, ply, future, google-gax, gapic-google-cloud-vision-v1, google-cloud-vision
Successfully installed cachetools-2.0.0 dill-0.2.6 future-0.16.0 gapic-google-cloud-vision-v1-0.90.3 google-auth-1.0.1 google-auth-httplib2-0.0.2 google-cloud-core-0.24.1 google-cloud-vision-0.24.0 google-gax-0.15.12 googleapis-common-protos-1.5.2 grpcio-1.3.0 httplib2-0.10.3 oauth2client-3.0.0 ply-3.8 proto-google-cloud-vision-v1-0.90.3 protobuf-3.3.0 pyasn1-0.2.3 pyasn1-modules-0.0.8 requests-2.14.2 rsa-3.4.2

And that enum34 is installed on Python 2.7

Processing ./google_cloud_vision-0.24.0-py2.py3-none-any.whl
Collecting enum34; python_version < "3.4" (from google-cloud-vision==0.24.0)
Using cached enum34-1.1.6-py2-none-any.whl
Collecting google-cloud-core<0.25dev,>=0.24.0 (from google-cloud-vision==0.24.0)
Using cached google_cloud_core-0.24.1-py2.py3-none-any.whl
Collecting gapic-google-cloud-vision-v1<0.91dev,>=0.90.3 (from google-cloud-vision==0.24.0)
Collecting protobuf>=3.0.0 (from google-cloud-core<0.25dev,>=0.24.0->google-cloud-vision==0.24.0)
Requirement already satisfied: six in /private/tmp/env/lib/python2.7/site-packages (from google-cloud-core<0.25dev,>=0.24.0->google-cloud-vision==0.24.0)
Collecting google-auth-httplib2 (from google-cloud-core<0.25dev,>=0.24.0->google-cloud-vision==0.24.0)
Using cached google_auth_httplib2-0.0.2-py2.py3-none-any.whl
Collecting googleapis-common-protos>=1.3.4 (from google-cloud-core<0.25dev,>=0.24.0->google-cloud-vision==0.24.0)
Collecting google-auth<2.0.0dev,>=0.4.0 (from google-cloud-core<0.25dev,>=0.24.0->google-cloud-vision==0.24.0)
Using cached google_auth-1.0.1-py2.py3-none-any.whl
Collecting httplib2>=0.9.1 (from google-cloud-core<0.25dev,>=0.24.0->google-cloud-vision==0.24.0)
Collecting proto-google-cloud-vision-v1[grpc]<0.91dev,>=0.90.3 (from gapic-google-cloud-vision-v1<0.91dev,>=0.90.3->google-cloud-vision==0.24.0)
Collecting google-gax<0.16dev,>=0.15.7 (from gapic-google-cloud-vision-v1<0.91dev,>=0.90.3->google-cloud-vision==0.24.0)
Collecting oauth2client<4.0dev,>=2.0.0 (from gapic-google-cloud-vision-v1<0.91dev,>=0.90.3->google-cloud-vision==0.24.0)
Requirement already satisfied: setuptools in /private/tmp/env/lib/python2.7/site-packages (from protobuf>=3.0.0->google-cloud-core<0.25dev,>=0.24.0->google-cloud-vision==0.24.0)
Collecting pyasn1>=0.1.7 (from google-auth-httplib2->google-cloud-core<0.25dev,>=0.24.0->google-cloud-vision==0.24.0)
Using cached pyasn1-0.2.3-py2.py3-none-any.whl
Collecting rsa>=3.1.4 (from google-auth-httplib2->google-cloud-core<0.25dev,>=0.24.0->google-cloud-vision==0.24.0)
Using cached rsa-3.4.2-py2.py3-none-any.whl
Collecting pyasn1-modules>=0.0.5 (from google-auth-httplib2->google-cloud-core<0.25dev,>=0.24.0->google-cloud-vision==0.24.0)
Using cached pyasn1_modules-0.0.8-py2.py3-none-any.whl
Collecting cachetools>=2.0.0 (from google-auth<2.0.0dev,>=0.4.0->google-cloud-core<0.25dev,>=0.24.0->google-cloud-vision==0.24.0)
Using cached cachetools-2.0.0-py2.py3-none-any.whl
Collecting grpcio<2.0dev,>=1.0.2; extra == "grpc" (from proto-google-cloud-vision-v1[grpc]<0.91dev,>=0.90.3->gapic-google-cloud-vision-v1<0.91dev,>=0.90.3->google-cloud-vision==0.24.0)
Using cached grpcio-1.3.0-cp27-cp27m-macosx_10_10_intel.whl
Collecting ply==3.8 (from google-gax<0.16dev,>=0.15.7->gapic-google-cloud-vision-v1<0.91dev,>=0.90.3->google-cloud-vision==0.24.0)
Collecting future<0.17dev,>=0.16.0 (from google-gax<0.16dev,>=0.15.7->gapic-google-cloud-vision-v1<0.91dev,>=0.90.3->google-cloud-vision==0.24.0)
Collecting requests<3.0dev,>=2.13.0 (from google-gax<0.16dev,>=0.15.7->gapic-google-cloud-vision-v1<0.91dev,>=0.90.3->google-cloud-vision==0.24.0)
Using cached requests-2.14.2-py2.py3-none-any.whl
Collecting dill<0.3dev,>=0.2.5 (from google-gax<0.16dev,>=0.15.7->gapic-google-cloud-vision-v1<0.91dev,>=0.90.3->google-cloud-vision==0.24.0)
Requirement already satisfied: packaging>=16.8 in /private/tmp/env/lib/python2.7/site-packages (from setuptools->protobuf>=3.0.0->google-cloud-core<0.25dev,>=0.24.0->google-cloud-vision==0.24.0)
Requirement already satisfied: appdirs>=1.4.0 in /private/tmp/env/lib/python2.7/site-packages (from setuptools->protobuf>=3.0.0->google-cloud-core<0.25dev,>=0.24.0->google-cloud-vision==0.24.0)
Collecting futures>=2.2.0 (from grpcio<2.0dev,>=1.0.2; extra == "grpc"->proto-google-cloud-vision-v1[grpc]<0.91dev,>=0.90.3->gapic-google-cloud-vision-v1<0.91dev,>=0.90.3->google-cloud-vision==0.24.0)
Using cached futures-3.1.1-py2-none-any.whl
Requirement already satisfied: pyparsing in /private/tmp/env/lib/python2.7/site-packages (from packaging>=16.8->setuptools->protobuf>=3.0.0->google-cloud-core<0.25dev,>=0.24.0->google-cloud-vision==0.24.0)
Installing collected packages: enum34, protobuf, pyasn1, pyasn1-modules, rsa, cachetools, google-auth, google-auth-httplib2, googleapis-common-protos, httplib2, google-cloud-core, oauth2client, futures, grpcio, proto-google-cloud-vision-v1, ply, future, requests, dill, google-gax, gapic-google-cloud-vision-v1, google-cloud-vision
Successfully installed cachetools-2.0.0 dill-0.2.6 enum34-1.1.6 future-0.16.0 futures-3.1.1 gapic-google-cloud-vision-v1-0.90.3 google-auth-1.0.1 google-auth-httplib2-0.0.2 google-cloud-core-0.24.1 google-cloud-vision-0.24.0 google-gax-0.15.12 googleapis-common-protos-1.5.2 grpcio-1.3.0 httplib2-0.10.3 oauth2client-3.0.0 ply-3.8 proto-google-cloud-vision-v1-0.90.3 protobuf-3.3.0 pyasn1-0.2.3 pyasn1-modules-0.0.8 requests-2.14.2 rsa-3.4.2