Why does Pip ignore conflicting dependencies?

Question

If I create a dummy package - here / tmp / example _package / setup.py (note the requirements):

from distutils.core import setup setup(name='my_project', description="Just a test project", version="1.0", py_modules=['sample'], install_requires=['requests > 0.12']) 

Here / tmp / example_package / sample.py:

 import requests def get_example(): return requests.get("http://www.example.com") 

Now I create virtualenv:

 $ virtualenv /tmp/foobar --distribute -p python2.7 Running virtualenv with interpreter /usr/bin/python2.7 New python executable in /tmp/foobar/bin/python2.7 Also creating executable in /tmp/foobar/bin/python Installing distribute.................................................................................................................................................................................................done. Installing pip................done. $ source /tmp/foobar/bin/activate 

I create require.pip with conflicting requirements :

 # this requires requests > 0.12: file:///tmp/example_package # but this conflicts: requests==0.9.0 

Pip happily installs this:

 $ pip install -r requirements.pip [18:40:10] Unpacking ./example_package Running setup.py egg_info for package from file:///tmp/example_package Downloading/unpacking requests==0.9.0 (from -r requirements.pip (line 3)) Downloading requests-0.9.0.tar.gz (55Kb): 55Kb downloaded Running setup.py egg_info for package requests Downloading/unpacking certifi>=0.0.4 (from requests==0.9.0->-r requirements.pip (line 3)) Downloading certifi-0.0.8.tar.gz (118Kb): 118Kb downloaded Running setup.py egg_info for package certifi Installing collected packages: requests, my-project, certifi Running setup.py install for requests Running setup.py install for my-project Running setup.py install for certifi Successfully installed requests my-project certifi Cleaning up... 

Why does Pip allow this? My example_package will not work because its requirements are not met.

Answer 1

This is Pip's limitation. Requirements file exceeds package requirements. See https://github.com/pypa/pip/issues/775#issuecomment-12748095

Answer 2

Looking at the source of the pip, it seems that it should recursively add all the requirements to one large RequirementSet ... and then fly out with the exception of "Duplicate requirement" ...

Hmm .. are you sure your setup.py is correct?

Distutils has a requires keyword but not install_requires : http://docs.python.org/2/distutils/setupscript.html#relationships-between-distributions-and-packages

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