Python Forum

Hello together,
i just finished my first own package but facing a problem when importing and executing things from outside:
I made a very minimal example as demonstration:

Folder "mymodule" contains:

#__init__.py
# empty

#constants.py
my_const = 42

#function.py
def my_func():
       print(my_const)

On the same level as mymodule is :

# test.py
from mymodule.function import my_func
my_func()

Unfortunately i get the error message: "no module named 'constant' " which confuses me since i can import constant in function.py properly.

Question: Why is that? ( Maybe this code should that never be necessary - let me know anything you have in mind :)

Thank you very much,
Bock

PS: how can i make a "tab" in the python brackets of the thread editor?

Please post the error message and the steps required to produce. Also post information about rhe directory structure.

(Mar-03-2023, 11:12 AM)Bock Wrote: [ -> ]Unfortunately i get the error message: "no module named 'constant' "

According to your post, the module is named 'constants' and not 'constant'. Could this be the error?

You could try a relative import in function.py

from .constants import my_const

Note that 'relative' import means relative to the python packages hierarchy, not the file system's directories tree.

As you see all files as you describe.

C:\Python310\mymodule
λ ls
__init__.py  constants.py  function.py  test.py 

my_func() will never work have to change to this.

#function.py
from mymodule.constants import my_const

def my_func():
    print(my_const)

Now can run test.py,and it will work.

C:\Python310\mymodule
λ python test.py
42

A little more about how a package works.

C:\Python310\mymodule
λ ptpython
>>> import mymodule
>>>
>>> dir(mymodule)
['__builtins__', '__cached__', '__doc__', '__file__', '__loader__', '__name__', '__package__', '__path__', '__spec__'

As see here so is nothing added to namespace if just import like this.
I like to modify so can just to simple import like this and files are added.
In __init__.py

import mymodule.constants
import mymodule.function

Test again.

C:\Python310\mymodule
λ ptpython
>>> import mymodule
>>>
>>> dir(mymodule)
['__builtins__', '__cached__', '__doc__', '__file__', '__loader__', '__name__', '__package__', '__path__', '__spec__', 'constants', 'function', 'mymodule']

>>> mymodule.constants.my_const
42

>>> mymodule.function.my_func()
42

Or can import like this without modify __init__.py.
This will bring constants and function into the namespace of package.

C:\Python310\mymodule
λ ptpython
>>> from mymodule import constants, function
>>> constants.my_const
42
>>> function.my_func()
42

---

Some more examples you can look in link in this post.