What does __name__ == "__main__" mean in Python?

[cashinclean123-eng]

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What does name == "main" mean in Python?

[lorddrago12]

__name__ is a special variable that Python sets automatically: when a file is run directly, __name__ is set to "__main__", but when the same file is imported into another file, __name__ becomes the module’s name. The condition if __name__ == "__main__": is therefore used to make sure certain code runs only when the file is executed directly and not when it’s imported, which helps prevent accidental execution and allows the file to be reused as a module in other programs.

[alexhozt]

The condition if name == "main": is a fundamental pattern in Python that acts as a controlled entry point. Its main function is to differentiate whether a .py file is being run directly as the main program or if it is being imported as a module by another script. Python automatically assigns the value "main" to the special variable name only when that file is executed by the interpreter. This allows you to create files that are both reusable modules (with functions and classes) and executable programs, without the execution code being accidentally triggered during an import.

For example, in a file called my_utility.py:

def greet():
print("Hello from the module!")

if name == "main":
# This block ONLY runs if you do: python my_utility.py
print("Running as the main program...")
greet()

If another script imports it (import my_utility), the greet() function will be available, but the message "Running as the main program..." will not appear because name will be "my_utility" (not "main").

If you run it directly (python my_utility.py), the block under the if activates, showing both messages. This design is crucial for maintaining modularity, preventing unwanted side effects, and facilitating controlled tests within the same file.

[luc-garrido]

name is a special variable that Python sets automatically: when a file is run directly, name is set to "main", but when the same file is imported into another file, name becomes the module’s name. The condition if name == "main": is therefore used to make sure certain code runs only when the file is executed directly and not when it’s imported, which helps prevent accidental execution and allows the file to be reused as a module in other programs.

[flexycode]

Think of if __name__ == "__main__": as a security guard for your code. It checks how the file is being run before deciding what to execute.

Every Python file has a built-in variable called name. Python sets this variable automatically depending on how you use the file:

• If you run the file directly (e.g., clicking "Run" or typing python script.py), Python sets the name to "main".

• If you import the file into another script (e.g., import script), Python sets the name to the filename (e.g., "script").

[Im-diablo]

In Python, name is a special built-in variable automatically set by the interpreter: when a file is run directly, name is set to "main", but when the same file is imported into another script, name becomes the module’s name. The condition if name == "main": is therefore used to ensure that certain code runs only when the file is executed directly and not when it is imported, which prevents accidental execution during imports and allows the file to be reused as a clean, modular component in other programs.