How to Use __name__ in Python

09/12/2021

Contents

In this article, you will learn how to use __name__ in Python.

How to Use __name__

The __name__ is a special built-in variable in Python that is automatically set when a module is executed. It is a string that holds the name of the module as a string. The value of __name__ can be either “__main__” or the name of the module, depending on how the module is being executed.

Here’s how you can use __name__ in Python:

if __name__ == "__main__":
    # code that only runs when this module is run as the main program
    # (not imported as a module)
    # ...
else:
    # code that only runs when this module is imported as a module
    # ...

This can be useful when writing scripts or reusable code modules. When a module is executed as the main program, the code inside the if __name__ == “__main__”: block will be executed, but when the module is imported as a module into another script, the code inside the if __name__ == “__main__”: block will not be executed, but the rest of the code will.

For example, consider the following module, example.py:

def some_function():
    print("This function is defined in the module")

if __name__ == "__main__":
    print("This module is being run as the main program")
    some_function()

If you run example.py as the main program, you will get the following output:

This module is being run as the main program
This function is defined in the module

If you import example as a module into another script, you will not see the output This module is being run as the main program, but you will be able to call the some_function:

import example

example.some_function()
# Output: This function is defined in the module
#Python