Why simple import of module in same directory is not allowed

Question

I've created two modules in the same directory:

.
├── mod1.py
├── mod2.py

There is no __init__.py, I don't want to create this as a package, I'm just creating a simple script which I have modularized by breaking into different modules.

My intention is to run mod1.py using python mod1.py

~/junk/imports$ cat mod1.py 
from . import mod2

print(mod2.some_expr)


$ cat mod2.py
some_expr = 'hello world!'

Although I know that directly using import mod1 will work, but I'm deliberately not using it so that my module name doesn't clash with built in modules (which I felt is a good practice)

I'm getting the following errors with python2 and python3

~/junk/imports$ python3 --version
Python 3.4.3
kartik@kartik-lappy:~/junk/imports$ python3 mod1.py 
Traceback (most recent call last):
  File "mod1.py", line 1, in <module>
    from . import mod2
SystemError: Parent module '' not loaded, cannot perform relative import


~/junk/imports$ python2 --version
Python 2.7.11
~/junk/imports$ python2 mod1.py 
Traceback (most recent call last):
  File "mod1.py", line 1, in <module>
    from . import mod2
ValueError: Attempted relative import in non-package

Most of the questions like this on StackOverflow deal with packages, but I'm not using packages. I just want to run it as a simple script.

My question is not about how to do it, but I want to know the reason behind the above not working.

Why are you not using an __init__.py file? Wouldn't this mean that when python checks the . directory, it realises theres no init file and will throw an exception? i.e attempted relative import in non-package — Alan Kavanagh, May 28 '16 at 17:21
I'm not using `__init__.py` because I don't want to create a package. I'm just creating simple scripts. I want to understand the reason behind not allowing "explicit" relative imports. — Kartik Anand, May 28 '16 at 17:28

score 1 · Accepted Answer · edited May 23 '17 at 12:22

1

You shouldn't use relative, but absolute import:

import mod2
print(mod2.some_expr)

The documentation is pretty good, and this SO answers gives an alternative using importlib.

If a handmade module clash with a builtin module, the proper way to go is probably to rename it, eventually through addition of a {pre,suf}fix. Another is to use importlib.

The motivation underlying these limitation can be found in the PEP 328, and comes mainly from BDFL preferences, over all other solutions.

edited May 23 '17 at 12:22

Community

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answered May 28 '16 at 17:18

aluriak

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I know I should, but here I'm using explicit relative import. Is there a reason why it is not recommended? – Kartik Anand May 28 '16 at 17:20
[PEP 328](https://www.python.org/dev/peps/pep-0328) gives informations about imports. As far as i know, relative imports are generally not recommended, and only available inside packages. From the PEP: *all import statements be absolute by default (searching sys.path only) with special syntax (leading dots) for accessing package-relative imports.* – aluriak May 28 '16 at 17:23
I meant to import `mod2` only. I've corrected the question! – Kartik Anand May 28 '16 at 17:27
I can see the rationale for using absolute imports with package. But what about non-packages, for simple scripts, I thought relative imports should work. – Kartik Anand May 28 '16 at 17:32
[Python glossaries](https://docs.python.org/3/glossary.html#term-package) explains that that all packages are modules, but not all modules are packages. The `__path__` attribute, specific to packages, allows them to have a relative import. While modules that are not packages have no `__path__` attribute, it's impossible to get a relative import. – aluriak May 28 '16 at 17:38

Why simple import of module in same directory is not allowed

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