我如何使用PYTHONPATH

Question

I can't seem to get my module and class files to load from my script, but it loads fine from the REPL

I have a fairly simply project structure

/home/user/project/
/home/user/project/bin/
/home/user/project/bin/myscript.py
/home/user/project/lib/
/home/user/project/lib/mymodule/__init__.py
/home/user/project/lib/mymodule/example.py

When I run the Python REPL, everything runs just fine.

$export PYTHONPATH=./lib:$PYTHONPATH # Making sure that the REPL and script have access
$python
Python 2.7.8 blashblahblah
...
>from mymodule.example import MyClass
>test = MyClass()
>^D
$./bin/myscript.py
Traceback (most recent call last):
  File "myscript.py", line 5, in <module>
    from mymodule.example import MyClass
  File "/path/to/myscript.py", line 5, in <module>
    from mymodule.example import MyClass
ImportError: No module named example

Answer 1

I'm gonna answer my own question here. It turns out that the scripts name was 'mymodule.py'

bin/
bin/mymodule.py
lib/
lib/mymodule/
lib/mymodule/__init__.py
lib/mymodule/example.py

When importing from the repl, the pythonpath resolves to the lib/mymodule module, and the code is loaded correctly (mostly). When running the script mymodule.py , the python interpreter prepends the script's directory bin/ to the pythonpath . The script then sees an import statement(s) for mymodule, and sources itself. When it fails to find a namespace that can be traversed to look for 'example' within the script, it throws the ImportError.

The solution is to either rename the module or rename the script, (eg bin/my_module.py ) so that the namespaces don't collide.