Using global variables between files?

python

best-practices

global-variables

module-management

byNikita Barsukov·Mar 9, 2025

The key to sharing global variables across files is a dedicated module. Here's the fast track to global glory:

Create a globals.py:

# Behold! Our global variable arises!
shared_data = "Hello from globals!"

Summon it in other files, let's say main.py:

from globals import shared_data

# Ding dong! Who's there? Globals!
print(shared_data)  # Outputs: Hello from globals!

This tactic ensures that shared_data can be accessed and manipulated consistently across your modules.

Get into the groove with global variable management

Why we choose a separate module for globals?

We use a separate module for global variables for three big reasons:

Clear Code Organization: Like a tidy desk, it puts all your important things in one place.
Namespace sanity: Avoids name-calling fights among your globals.
Single Source of Truth: Your app will speak the truth, the whole truth and nothing but the truth.

Initialization and access patterns: Doing it right!

Here are some best practices for initialization and access:

Initialize Once: Start your globals in the main command center to prevent a global mess.
Avoid from module import *: This can lead to a clash of clans and reduce readability.
Order Matters: Keep your import orders correct, just like in a fine dining place.

The good of encapsulating global state

Wrap your global state in a blanket of functions:

# globals.py
def let_the_games_begin():
    global shared_data
    shared_data = "Let's Roll!"

# main.py
import globals
globals.let_the_games_begin()
print(globals.shared_data)  # Outputs: Let's Roll!

By using an initializing function, you can orchestrate how your global variables stand up and salute!

Design: Go modular or bust!

To keep global monster away, we use:

Function arguments: Pass arguments instead of screaming globals across modules.
Class instances: Keep state alteration in check and personal.
Constants: Use immutables when possible to prevent misunderstood edits.

Be responsibly while playing with globals

Remember these wise words while at play:

Minimize usage: It's easy to go overboard. Keep your globals neat and clean.
Comments: Document what each global brushes its teeth with!
Refactoring: Clean up after your globals. You'll thank yourself later.

When globals can't be avoided, embrace them safely

If globals are inevitable, follow these safety measures:

Thread with care: Use locking if many threads access your precious globals.
Dynamic changes: Watch out for those mutable data types.
Testing: Globals can make your code a testing nightmare. Use mock objects or dependency injection to get some sleep.

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