Python Tips — What is “if __name__ == __main__”?

What is if __name__ == "__main__"

When diving into Python, beginners often come across the seemingly cryptic line: if __name__ == "__main__":. It's a common construct in scripts and applications, and understanding its significance is a rite of passage in one's Python journey.

This specific code pattern acts as a safeguard, preventing unintended execution of scripts. When this protective mechanism is absent, several issues arise:

• When another script imports a script missing this safeguard (for instance, import my_script_without_protection), it inadvertently causes the imported script to run immediately upon importing, using the command line arguments of the importing script. Such behavior is rarely intended.
• Suppose a custom class resides in the script lacking this protective measure and it’s serialized into a pickle file. When this pickle file is deserialized in a different script, it prompts the importing of the unprotected script, leading to the same unintended execution as mentioned in the first point.

Modules vs Scripts in Python

In Python, every file with the .py extension is essentially a module. This module can define functions, classes, and variables. It can also include runnable code…