Installing another source distribution in setup.py?

Question

I have a dependency that's not on PyPi , but I have it in a source distribution tar file. Is there anyway to get setup.py to use the tar to install the dependency?

This doesn't work because dependency.tar.gz is not available after the project gets into an sdist:

from setuptools.command.install import install

class MyInstall(install):
    def run(self):
        os.system('pip install -U dependency.tar.gz')


setup(
      ...
      cmdclass={'install': MyInstall}
 )

Answer 1

Setuptools documentation actually covers installation of dependencies that aren't registered in PyPI.

http://pythonhosted.org/setuptools/setuptools.html#dependencies-that-aren-t-in-pypi