How come I can't get the exactly result to *pip install* by manually *python setup.py install*?

Question

I like to figure out the myth behind Python's namespace packages by setuptools, and here is what I did test.

• Make a virtual environment by virtualenv.
• Find a namespaced package on PyPI.
• Install that package by pip install.
• Check the installed file hierarchy.

The package I played with is zope.interface and it worked well with the following file hierarchy on my virtualenv:

~virenv/.../site-packages/zope.interface-3.8.0-py2.6-nspkg.pth
                         /zope.interface-3.8.0-py2.6.egg-info/
                         /zope/
                              /interface/
                                        /...

Everything looked fine and I love the way zope.interface got installed as a real namespaced package (under folder zope).

Then, I did another test and that's the question I would like to ask for your help. I downloaded the tared zope.interface source file. I liked to play it manually again

• Make a virtual environment by virtualenv.
• Untar the zope.interface into somewhere.
• Install the package by python setup.py install.
• Go check what happened in site-packages.

The site-packages looks like this:

~virenv/../site-packages/zope.interface-...egg/
                                              /zope/
                                                   /__init__.py
                                                   /interface/
                                              /EGG-INFO/

Q. How come I can't get the exactly result to pip install by manually python setup.py install?

Answer 1

pip uses setup.py internally. It just passes additional option to it. To reproduce what pip is doing, execute

python setup.py install --single-version-externally-managed

You can also run pip -vv to see exactly which commands are run.