Execute a Python script post install using distutils / setuptools

The way to address these deficiences is:

1. Get the full path to the Python interpreter executing setup.py from sys.executable.

2. Classes inheriting from distutils.cmd.Command (such as distutils.command.install.install which we use here) implement the execute method, which executes a given function in a “safe way” i.e. respecting the dry-run flag.

   Note however that the --dry-run option is currently broken and does not work as intended anyway.

I ended up with the following solution:

import os, sys
from distutils.core import setup
from distutils.command.install import install as _install


def _post_install(dir):
    from subprocess import call
    call([sys.executable, 'scriptname.py'],
         cwd=os.path.join(dir, 'packagename'))


class install(_install):
    def run(self):
        _install.run(self)
        self.execute(_post_install, (self.install_lib,),
                     msg="Running post install task")


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

Note that I use the class name install for my derived class because that is what python setup.py --help-commands will use.