req.py 文件源码

def setup_py(self):
        try:
            import setuptools
        except ImportError:
            # Setuptools is not available
            raise InstallationError(
                "setuptools must be installed to install from a source "
                "distribution"
            )

        setup_file = 'setup.py'

        if self.editable_options and 'subdirectory' in self.editable_options:
            setup_py = os.path.join(self.source_dir,
                                    self.editable_options['subdirectory'],
                                    setup_file)

        else:
            setup_py = os.path.join(self.source_dir, setup_file)

        # Python2 __file__ should not be unicode
        if six.PY2 and isinstance(setup_py, six.text_type):
            setup_py = setup_py.encode(sys.getfilesystemencoding())

        return setup_py