问题
Environment: debian 4.0
Python 2.4
My 'project' is installed in:
/usr/lib/python2.4/site-packages/project.
But I want to use my working copy instead of the installed one which is located in:
/home/me/dev/project/src
So what I do is:
export PYTHONPATH=/home/me/dev/project/src
ipython
import foo # which is in src
foo.__file__*/usr/lib/python2.4/site-packages/project/foo.py*
instead of :
/home/me/dev/project/src/project/foo.py
How come? I try to check the pathes (having done the export above) and what I see is:
import sys,os
sys.path
['', '/usr/bin', '/usr/lib/python2.4/site-packages', '/home/me/dev/project/src', '/usr/lib/python24.zip', '/usr/lib/python2.4', '/usr/lib/python2.4/plat-linux2', '/usr/lib/python2.4/lib-tk', '/usr/lib/python2.4/lib-dynload', '/usr/local/lib/python2.4/site-packages', '/usr/lib/python2.4/site-packages/PIL', '/var/lib/python-support/python2.4', '/usr/lib/python2.4/site-packages/IPython/Extensions', '/home/me/.ipython']
os.environ['PYTHONPATH']
/home/me/dev/project/src
回答1:
According to python documentation, this is expected behavior: https://docs.python.org/2.4/lib/module-sys.html:
Notice that the script directory is inserted before the entries inserted as a result of PYTHONPATH.
Under python-2.6 it is different: http://docs.python.org/tutorial/modules.html#the-module-search-path
回答2:
I found the problem (I've missed early on when somebody pointed me to Where is Python's sys.path initialized from?).
It seems that easy_install creates a pth file /usr/lib/python2.4/site-packages/easy-install.pth which is then loaded by site.py. This inserts the site-packages path in the sys path before the PYTHONPATH. Not nice.
回答3:
I don't believe you have any control over where the PYTHONPATH gets inserted into the actual path list. But that's not the only way to modify the path - you can update sys.path yourself, before you try to import the project.
Edit: In your specific case, you can modify the path with
import sys
sys.path.insert(2, '/home/me/dev/project/src')
回答4:
I see '/usr/lib/python2.4/site-packages' in your path prior to '/home/me/dev/project/src', does that matter? What happens when you switch the two?
From the docs:
When PYTHONPATH is not set, or when the file is not found there, the search continues in an installation-dependent default path
So perhaps you didn't find your working copy on your PYTHONPATH as you had thought?
回答5:
Not a direct answer to you question, but you could also use a virtualenv to create a development environment. In that virtualenv you can then install your product in /home/me/dev/project/src as a development package: "python setup.py develop".
This way you don't have to change your PYTHONPATH manually. Just activate the virtualenv if you want to use the development code.
回答6:
I think you set up PYTHONPATH to /home/me/build/project/src since /home/me/dev/project/src does not appear in sys.path, but /home/me/build/project/src does.
回答7:
It sounds like the src directory doesn't have an __init__.py file. It's not a proper package.
来源：https://stackoverflow.com/questions/1001851/pythonpath-ignored