Using the [`path.py`](https://pypi.python.org/pypi/path.py) module would make this so much nicer!
```python
# in the imports
from path import path

# in your code
self.temp_dir = mkdtemp()
self.data_dir = path(__file__).realpath().parent / "data"
self.version0 = self.data_dir / "Version0_drafts.tar.gz"
self.version1 = self.data_dir / "Version1_drafts.tar.gz"
```
We're already using `path.py` in our project, and the documentation is here: http://pythonhosted.org/path.py/api.html