How to Achieve Cross-Module Variable Behavior in Python?

Cross-Module Variable in Python

In Python, the __debug__ variable is a convenient global variable available in all modules. However, creating another variable with similar behavior requires a different approach. Here's how to achieve this:

Global Module-Level Variable

If the variable need not be truly global (i.e., updated across modules when modified), a simple module-level variable can suffice.

Example:

a.py:

<code class="python">var = 1</code>

b.py:

<code class="python">import a
print(a.var)
import c
print(a.var)</code>

c.py:

<code class="python">import a
a.var = 2</code>

Test:

$ python b.py
# Output: 1 2

In this example, the var variable in a.py is accessible to both b.py and c.py. When c.py modifies var, the change is reflected in b.py as well, demonstrating its cross-module behavior.

Real-World Example:

Django, a popular web framework, uses a similar approach with its global_settings.py. Instead of variables, settings are defined as an object (django.conf.settings) that's imported into various Django apps.

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