Question

Why does my namespace import not work when I use the os.chdir() to get to the package dir from script?

For example here is my package structure to demonstrate the problem.

testpk/
testpk/bin
testpk/bin/runit.py
testpk/lib
testpk/lib/libcode.py
testpk/lib/__init__.py

here is my lib code which just prints ive been imported

print "I've been imported"

contents of runit.py

#!/usr/bin/python
import  sys, os

if __name__ == "__main__":
    os.chdir('/home/moorepe/src/testpk')   
    print "working path = " , os.getcwd()
    import lib.libcode 

If i run runit i get this error:

moorepe@halifax$ bin/runit.py 
Traceback (most recent call last):
  File "bin/runit.py", line 6, in <module>
    import lib.libcode 
ImportError: No module named lib.libcode

However testing this with python command line it works as expected:

    cd testpk
    python -c "import lib.libcode
    I've been imported

And this works from the bin dir:

cd testpk/bin
python -c "import os; os.chdir('/home/moorepe/src/testpk') ; import lib.libcode"
I've been imported

Can anyone explain what is going wrong?

So the reason this didnt work is that python uses the current dir as a path in addition to the PYTHONPATH.

so this code works by adding sys.path.append(“.”) because im forcing a current working dir as a path addition.

Answer 1

If you add a '.' for the current directory to the sys.path search folder list, then the os.chdir() will become effective and the import lib.libcode should start working:

File runit.py:

#!/usr/bin/python
import  sys, os

if __name__ == "__main__":
    sys.path[0:0] = ['.']  # prefix current directory to list
    os.chdir('/home/moorepe/src/testpk')
    print "working path =", os.getcwd()
    import lib.libcode