Import a python module without the .py extension

You can use the imp.load_source function (from the imp module), to load a module dynamically from a given file-system path.

import imp
foobar = imp.load_source('foobar', '/path/to/foobar')

This SO discussion also shows some interesting options.

Here is a solution for Python 3.4+:

from importlib.util import spec_from_loader, module_from_spec
from importlib.machinery import SourceFileLoader 

spec = spec_from_loader("foobar", SourceFileLoader("foobar", "/path/to/foobar"))
foobar = module_from_spec(spec)
spec.loader.exec_module(foobar)

Using spec_from_loader and explicitly specifying a SourceFileLoader will force the machinery to load the file as source, without trying to figure out the type of the file from the extension. This means that you can load the file even though it is not listed in importlib.machinery.SOURCE_SUFFIXES.

If you want to keep importing the file by name after the first load, add the module to sys.modules:

sys.modules['foobar'] = foobar

You can find an implementation of this function in a utility library I maintain called haggis. haggis.load.load_module has options for adding the module to sys.modules, setting a custom name, and injecting variables into the namespace for the code to use.

Like others have mentioned, you could use imp.load_source, but it will make your code more difficult to read. I would really only recommend it if you need to import modules whose names or paths aren't known until run-time.

What is your reason for not wanting to use the .py extension? The most common case for not wanting to use the .py extension, is because the python script is also run as an executable, but you still want other modules to be able to import it. If this is the case, it might be beneficial to move functionality into a .py file with a similar name, and then use foobar as a wrapper.