Using same library with different version across virtual environment

Question

I am working on a project in python which have dependencies in multiple modules.

As an example say my main module uses another 2 modules namely module_1 which needs library lib_version_1.5 and module_2 which uses the same library_but_version_1.8 .

Both module_1 and module_2 is running fine, now I am creating another module combining these two.

So how can I use virtual environment so that I can combine these two with all required libraries (different versions) ? Is it possible to get different version of the same library installed within a project having different sub modules?

Answer 1

Note that the python namingspace is quite powerful. Hope this small Example will help you.

The basic theory is that add the same libs with different versions into the python's class path and make them be different names so that there will not be overriding.

import os, sys
sys.path.insert(0, os.path.join(os.path.dirname(os.path.abspath(__file__)), 'libs'))

The above code will insert the third-part libs which under the directory of 'libs' that under your project's base directory.

Suppose that I need pycrypto with version 2.4.1 and 2.6.1, use pip install pycrypto==2.6.1 -t ./libs and ip install pycrypto==2.4.1 -t ./libs to install the two versions into a sub-directory under your project. Modify their name after you have installed one, otherwise it will override the existed one.

Modify their names to Crypto241 and Crypto261 seprately.

Let's say I will have two modules(ModuleWIthCrypto241, ModuleWithCrypto261) which will import pycrypto 2.4.1 and 2.6.1 seprately.

ModuleWithCrypto261 with code:

def getCryproVersion(baseDir):
    import os, sys
    sys.path.insert(0, os.path.join(baseDir, 'libs'))
    import Crypto261
    return Crypto261.__version__

ModuleWIthCrypto241 with code:

def getCryproVersion(baseDir):
    import os, sys
    sys.path.insert(0, os.path.join(baseDir, 'libs'))
    import Crypto241
    return Crypto241.__version__

Almost the same, just import the different version of pycrypto.

Then we have another script which try to get the two different version of pycrypto.modulewithdiffversion.py

What it looks like:

import os, sys

from com.x import ModuleWIthCrypto241
from com.x import ModuleWithCrypto261
if __name__ == '__main__':
    baseDir = os.path.dirname(os.path.abspath(__file__))
    print ModuleWIthCrypto241.getCryproVersion(baseDir)
    print ModuleWithCrypto261.getCryproVersion(baseDir)

Execute the main method, it will print out the two versions of the pycrypto:

2.4.1
2.6.1

Hope this will help you!