Create constants using a "settings" module?

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I am relatively new to Python. I am looking to create a "settings" module where various application-specific constants will be stored.

Here is how I am wanting to set up my code:

settings.py

CONSTANT = 'value'

script.py

import settings

def func():
    var = CONSTANT
    # do some more coding
    return var

I am getting a Python error stating:

global name 'CONSTANT' is not defined.

I have noticed on Django's source code their settings.py file has constants named just like I do. I am confused on how they can be imported to a script and referenced through the application.

EDIT

Thank you for all your answers! I tried the following:

import settings

print settings.CONSTANT

I get the same error

ImportError: cannot import name CONSTANT

python
10 Answers

This way is more efficient since it loads/evaluates your settings variables only once. It works well for all my Python projects.

pip install python-settings

Docs here: https://github.com/charlsagente/python-settings

You need a settings.py file with all your defined constants like:

# settings.py

DATABASE_HOST = '10.0.0.1'

Then you need to either set an env variable (export SETTINGS_MODULE=settings) or manually calling the configure method:

# something_else.py

from python_settings import settings
from . import settings as my_local_settings

settings.configure(my_local_settings) # configure() receives a python module

The utility also supports Lazy initialization for heavy to load objects, so when you run your python project it loads faster since it only evaluates the settings variable when its needed

# settings.py

from python_settings import LazySetting
from my_awesome_library import HeavyInitializationClass # Heavy to initialize object

LAZY_INITIALIZATION = LazySetting(HeavyInitializationClass, "127.0.0.1:4222") 
# LazySetting(Class, *args, **kwargs)

Just configure once and now call your variables where is needed:

# my_awesome_file.py

from python_settings import settings 

print(settings.DATABASE_HOST) # Will print '10.0.0.1'
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