Python pimping / monkey-patching

Question

I want to do a simple thing: monkey-patch datetime. I can't do that exactly, since datetime is a C class.

So I wrote the following code:

from datetime import datetime as _datetime

class datetime(_datetime):
    def withTimeAtMidnight(self):
        return self.replace(hour=0, minute=0, second=0, microsecond=0)

This is on a file called datetime.py inside a package I called pimp.

From the error message I'm given:

Traceback (most recent call last):
  File "run.py", line 1, in 
    from pimp.datetime import datetime
  File "/home/lg/src/project/library/pimp/datetime/datetime.py", line 1, in 
    from datetime import datetime as _datetime
ImportError: cannot import name datetime

I assume that I can't have a module called datetime importing anything from another module called datetime.

How should I proceed to keep my module and class named datetime?

Answer 1

Put you module into a package e.g., your_lib.datetime. You should not use datetime name for a top-level module.

If you are on Python 2 then add at the top:

from __future__ import absolute_import

to forbid implicit relative imports inside a package. Then if your directory structure is:

your_lib/
├── datetime.py
└── __init__.py

The following command works:

$ python -c 'import your_lib.datetime'

where datetime.py is:

from __future__ import absolute_import
from datetime import timedelta