python3.6和python3.7的导入区别

Question

I have a question about imports in python3.6 and python3.7.

I have the following dir structure:

.
└── lib
    ├── feature
    │   ├── feature1.py
    │   ├── __init__.py
    │   └── new
    │       ├── feature1.py
    │       └── __init__.py
    └── __init__.py

I have the following in the file lib/feature/__init__.py :

from lib.feature.feature1 import Feature1

I have the following in the file lib/feature/feature1.py :

import lib.feature.new.feature1 as new

class Feature1: pass

To recreate my environment, you can use the following:

mkdir lib
touch lib/__init__.py
mkdir -p lib/feature/new
echo "from lib.feature.feature1 import Feature1" > lib/feature/__init__.py
echo -e "import lib.feature.new.feature1 as new\nclass Feature1: pass" > lib/feature/feature1.py
touch lib/feature/new/__init__.py
touch lib/feature/new/feature1.py

When I run this code with python3.7 it works perfectly fine. When I run this code with python3.6, I get the following error:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "***/import_test/lib/feature/__init__.py", line 1, in <module>
    from lib.feature.feature1 import Feature1
  File "***/import_test/lib/feature/feature1.py", line 2, in <module>
    import lib.feature.new.feature1 as new
AttributeError: module 'lib' has no attribute 'feature'

So my question is, why is there a different outcome, when you run the code with python3.6 or python3.7?

To fix this issue, I have change the import in lib/feature/feature1.py to:

from .new import feature1 as new

To test, I just go to python and try to import the module:

import_test$ python
Python 3.6.8 (default, Dec 25 2018, 00:00:00)
[GCC 4.8.4] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import lib.feature

After that change, it works on python3.6 as well.

Thanks in advance.

Answer 1

这是一个带有“别名”导入（ import .. as ）的错误，在 Python 3.7 中得到修复。