Pip install zope.interface need the lateset setuptools (60.5.0), which can't work with python 2.7

[wei1224hf]

BUG/PROBLEM REPORT (OR OTHER COMMON ISSUE)

The zope.interface installation would use the latest setuptools , that's not good, because the latest setuptools can't work with python 2.7 .
Could anyone tell me how to install zope.interface 44.2 on python 2.7 ?

Thanks

What I did:

pip install twisted==20.3.0 # The lastest can't work on python2.7, 20.3.0 can

What I expect to happen:

Together install some other packages , work fine with python2.7

What actually happened:

`
Collecting zope.interface>=4.4.2 (from Twisted===20.3.0)
Collecting setuptools (from zope.interface>=4.4.2->Twisted==18.4.0)
Downloading setuptools-60.5.0.tar.gz

AttributeError: DistutilsMetaFinder instance has no attribute 'find_module'
`

What version of Python and Zope/Addons I am using:

Ubuntu 16.04 server rtt
python 2.7
ROS kinetic
pip 8.11

[d-maurer]

wei1224hf wrote at 2022-1-17 00:34 -0800:

The zope.interface installation would use the latest setuptools ... ... pip install twisted==20.3.0 # The lastest can't work on python2.7, 20.3.0 can ` ### What I expect to happen: Together install some other packages , work fine with python2.7 ### What actually happened: ` Collecting zope.interface>=4.4.2 (from Twisted===20.3.0) Collecting setuptools (from zope.interface>=4.4.2->Twisted==18.4.0) Downloading setuptools-60.5.0.tar.gz AttributeError: DistutilsMetaFinder instance has no attribute 'find_module'

That a new `setuptools` version is downloaded does not seem to be a `zope.interface` problem: I looked at the `install_requires` in the `setup.py` of `zope.interface` (master); it mentions `setuptools` but without any version specification. Thus, it should work with any `setuptools` version already present. Please try either of the following: * install a Python 2.7 compatible `setuptools` version before you try to install `twisted` * use `pip install` with a requirements or contraints file specifying the versions working in your case. We could work around the Python 2.7 problems of modern `setuptools` versions by specifying a sufficiently old `setuptools` version in `zope.interface`'s `install_requires`. **BUT** this likely would compromise many new installations. We could make the `setuptools` version dependent of Python 2 versus Python 3, **BUT** this would work only for the source distribution: to my knowledge, the eggs and wheel format is not versatile enough to support Python version dependent `install_requires`. `zope.interface==4.4.2` is old. I expect that its users must solve `setuptools` problems on their own (see above).

[cjwatson]

We could make the setuptools version dependent of Python 2 versus Python 3, BUT this would work only for the source distribution: to my knowledge, the eggs and wheel format is not versatile enough to support Python version dependent install_requires.

I think this is incorrect. You can write something like install_requires=["setuptools; python_version>='3'", "setuptools<45; python_version<'3'"] and that should work fine with wheels - it ends up in the wheel's METADATA file and pip understands it.

However, there's the question of whether zope.interface should be declaring setuptools in install_requires at all. It's only used in setup.py, so it should probably be in setup_requires instead. There may be some historical thorniness here, but still ...

[jensens]

pkg_resources as part of setuptools and is used for legacy namespace declaration here:
https://github.com/zopefoundation/zope.interface/blob/master/src/zope/__init__.py#L1

I am confused with the multiple ways of namespace declarations and why/when legacy needs to be used. Switching to PEP420 Style namespaces would remove any runtime dependency on setuptools.

[cjwatson]

Ah, I'd missed the use of pkg_resources.

As far as I know there isn't a sensible way to migrate from the pkg_resources namespace approach to PEP420, because all zope.* packages would have to be migrated simultaneously. PyPA says that trying to migrate is not advisable.

[d-maurer]

Colin Watson wrote at 2022-1-17 03:39 -0800:

However, there's the question of whether `zope.interface` should be declaring `setuptools` in `install_requires` at all. It's only used in `setup.py`, so it should probably be in `setup_requires` instead. There may be some historical thorniness here, but still ...

I used to add `setuptools` in my packages to make `zc.buildout` happy. Otherwise, it complained "uses namespace packages but does not depend on `setuptools`".

[graingert]

setuptools defines requires_python and so pip should only download a compatible version, it seems like upgrading pip in your 2.7 environment should fix this issue