Section 1.1: The Main Function

In Python, scripts typically execute from the top down. However, the main() function serves as the primary entry point for execution. When defined, the entire script compiles, but execution begins at this point.

• Parameters: The main() function can accept parameters if necessary, and it's conventionally called at the end of the script.

Section 1.2: Understanding __main__

The double underscores around __main__ signify that it is a special identifier. If this is not explicitly defined, Python runs the script from top to bottom. If specified, execution starts at this entry point:

>>> print(__main__)

Traceback (most recent call last):

File "<stdin>", line 1, in <module>

NameError: name '__main__' is not defined. Did you mean: '__name__'?

>>> print(type(__main__))

Traceback (most recent call last):

File "<stdin>", line 1, in <module>

NameError: name '__main__' is not defined. Did you mean: '__name__'?

Section 1.3: The __name__ Variable

The __name__ variable is a built-in special string that indicates the name of the module being executed. When a script is run directly, __name__ is assigned the value __main__, which you can confirm through:

>>> print(__name__)

__main__

>>> print(type(__name__))

<class 'str'>

Section 1.4: Conditional Execution with __name__

To ensure code runs only when a script is executed directly, you can use the following conditional statement:

if __name__ == '__main__':

main()

This condition evaluates to True when the script is executed directly, allowing the main() function to run. Conversely, if the script is imported as a module, this block will not execute, preventing unintended side effects.