Import module from one python install into another

Question

I am under Ubuntu 16.04 LTS.

I have two python installations. I am actually using them via pvpython, but this is likely irrelevant for the present question. The versions are:

1. Python 2.7.12, installed with apt-get, residing in system dirs.
2. Python 2.7.11, residing in ~/apps/ParaView-5.4.1-Qt5-OpenGL2-MPI-Linux-64bit, simply expanded from a tar file. To get the python prompt I run ~/apps/ParaView-5.4.1-Qt5-OpenGL2-MPI-Linux-64bit/bin/pvpython.

I mean to use readline from version 1 in version 2 (since it does not have its own, strange as it may be). To do this:

1. Find where is readline in version 1:

   >>> import readline
   >>> readline.__file__
   '/usr/lib/python2.7/lib-dynload/readline.x86_64-linux-gnu.so'
   

2. Use it in version 2, following this. I placed needed stuff in a directory dir1 which is an element of sys.path (I tried with both /home/santiago/apps/ParaView-5.4.1-Qt5-OpenGL2-MPI-Linux-64bit/lib/python2.7 and /home/santiago/apps/ParaView-5.4.1-Qt5-OpenGL2-MPI-Linux-64bit/lib/python2.7/lib-dynload).

   2.1. Get the .so file.

   $ cd dir1
   $ ln -s /usr/lib/python2.7/lib-dynload/readline.x86_64-linux-gnu.so
   

   2.2. Create readline.py

   $ nano readline.py
   

   with contents (as per ref above):

   def __bootstrap():
   global __bootstrap, __loader__, __file__
   import sys, pkg_resources, imp
   __file__ = pkg_resources.resource_filename(__name__,'readline.x86_64-linux-gnu.so')
   __loader__ = None; del __bootstrap, __loader__
   imp.load_dynamic(__name__,__file__)
   __bootstrap()
   

Now when I use version 2 with ~/apps/ParaView-5.4.1-Qt5-OpenGL2-MPI-Linux-64bit/bin/pvpython, I still get the error (that I wanted to get rid of)

ImportError: No module named readline

from an import in my ~/.pythonrc.

How can I import readline from version 1 into version 2?

Answer 1

I managed to solve this. The key was to link with the name readline.so instead of the original name. The rest was irrelevant.

In 2.1 of the OP:

$ cd ~/apps/ParaView-5.4.1-Qt5-OpenGL2-MPI-Linux-64bit/lib/python2.7/lib-dynload
$ ln -s /usr/lib/python2.7/lib-dynload/readline.x86_64-linux-gnu.so readline.so

That is it. It turns out that readline.py with __bootstrap (item 2.2) was not needed.