Import binary package from different directory

Question

I have the following directory structure:

root
  /src
    file1.py
    file2.py
  /libs
    __init__.py
    package.so

I wish to import package.so within file1.py.

I've tried the following import statements to no avail:

from .libs.package import func
from libs.package import func
from .libs import package
from libs import package

I want to avoid having to set PYTHONPATH / sys.path.

Is there a simple way to do this? I assume the issue is due to the package being a shared object and not just a Python file - I don't have access to the source code for it.

Thanks, Adam

Answer 1

If you are intent on not using sys.path.append to import the file, I was able to do it using the following snippet in file1.py:

import imp
import os
file = os.sep+os.path.join(*os.path.realpath(__file__).split(os.sep)[:-1]+['..','libs','package.so'])
package = imp.load_source('root.libs.package', file)
print package.a()

Which prints <root.libs.package.a instance at 0x101845518>. Note that my package.so file is just a python file that defines a dummy class a so that I could test importing it. From what I have read, I believe that replacing imp.load_source with imp.load_dynamic may be what you want.

Breaking it down:

os.path.realpath(__file__).split(os.sep)[:-1] gets you the path to the directory the currently-running script is in, as a list of strings.

+['..','libs','package.so'] concatenates a list containing the parent directory (..), the libs directory, and your filename to that list, so that os.path.join will build the full path to the package.so file.

os.path.join(*[that list]) unpacks the list elements into arguments to os.path.join, and joins the strings with os.sep. I also add a leading os.sep since it is an absolute path.

imp.load_source returns a module with the name root.libs.package loaded from the file path.

This source was useful for writing this answer, and here are the docs for the imp module, which you might also find useful.