尽管有 __init__.py，Python 仍无法导入自定义模块

Question

I have a folder with a __init__.py

File __init__.py:

#!/usr/bin/python2
flags="test"

File main.py:

#!/usr/bin/python2
import foldername

def main():
    print foldername.flags

if __name__ == '__main__':
main()

Now, when I run ./main.py (from inside the folder), I get the error

ImportError: No module named foldername

Answer 1

Run from the parent folder for foldername :

    $ python -m foldername.main

If you rename main.py to __main__.py then you could run it as (since Python 2.7):

    $ python -m foldername

python -m adds implicitly current directory to your python path ( sys.path ).

Parent Folder/
└── foldername
    ├── __init__.py
    │   #    flags="test"
    └── __main__.py
        #    import foldername
        #   
        #    def main():
        #        print foldername.flags
        #   
        #    if __name__=="__main__":
        #        main()

If the parent directory for foldername is in your python path then you could run the above commands from any directory.

Answer 2

PYTHONPATH issue. Make sure that "foldername" is available in your path. If you are running it from inside "foldername" it might not be available. Try running from the parent of "foldername".

Here is a question about finding your PYTHONPATH .

Answer 3

Make sure your layout is like this:

./folder/__init__.py
./main.py

and there is not file named folder.py !

Change to the parent folder, so that ls folder/__init__.py works.

Next try running python -c "import folder" .

Answer 4

If you want to import the a module in python3 simply go to the root folder

python3 -mModuleName

Make sure you do not remove the -m before the module name and then this you can import this module anywhere inside the project directory.