What is if __name__ == "__main__"?
In Python, the __name__ attribute is a special built-in variable that holds the name of the current module or script. When the Python interpreter runs a script or module, it assigns the value __main__ to the __name__ variable if the script is being executed as the main program.
The condition if __name__ == '__main__': is commonly used to differentiate between whether a script is being run as the main program or if it's being imported as a module into another script. This allows you to include code that should only run when the script is executed directly and not when it's imported as a module.
Detailed explanation with an example:
Suppose you have two Python files: main_script.py and module_example.py.Contents of module_example.py:
When you run module_example.py directly, you'll see the output:
When you run main_script.py, you'll see the output:
Notice that when you run module_example.py directly, the condition if __name__ == '__main__': is true, and the code block under it is executed. However, when you import module_example in main_script.py, the condition is false because __name__ is set to module_example, and the code block under it is not executed.
The __name__ == '__main__' is a common Python idiom used to check if a script is being executed as the main program or imported as a module. It allows you to include code that should only run when the script is executed directly.