如何修复名称未在 Python 中定义

Question

I am running a python project like this:

project
  Test.py
  COMMON.py
  SYSTEM.py
  PTEST1
    Hello.py

when run the code "Test.py" it will show NameError, I am not sure why?

But if I replaced the "from SYSTEM import *" with "from COMMON import *" in Test.py and PTEST1/Hello.py, it works as expect.

#Test.py is like this:

from SYSTEM import *
myvalue.Hello.printf()

# COMMON.py is like this:

myvalue = lambda: None
from PTEST1.Hello import Hello
myvalue.Hello = Hello

# SYSTEM.py is like this:

from COMMON import *

#PTEST1/Hello.py
from SYSTEM import *

class Hello():   
    @staticmethod
    def printf():
        print("Hello1")
        print(vars(myvalue))

I expect there is no "NameError" by not changing import code. BTW, my python is 3.6+

Answer 1

Good practice is to give filenames in lowercase.

It looks like you are creating a Python project under project/ . Any directory needs to have a file __init__.py in every directory in order for it to be discovered in Python.

You then need to refer to modules by their full name (not relative naming).

So the directory structure should be:

project/
  __init__.py
  test.py
  common.py
  system.py
  ptest1/
    __init__.py
    hello.py

Every time you refer to file you should give the full path.

# import everything from hello.py
from project.ptest1.hello import *

# import everything from common.py
from project.common import *

# import everything from system.py
from project.system import *