What Does `if __name__ == '__main__':` Do in Python?

What does 'if name == "__main__":' do?

When running a Python script as the main program, it assigns a hard-coded string "__main__" to the name variable. If the script is imported by another module, name is assigned to the name used for the import; for example, if another script imports foo.py as import foo, then the name variable in foo.py becomes "foo".

By checking if name is equal to "__main__", it ensures that the code within the guard is only executed when the script is run directly, not when it's imported as a module.

Why is this necessary?

Including the if __name__ == "__main__": statement offers several benefits:

1. Prevention of unwanted execution: If the script is imported by another module, the code within the guard won't be executed, preventing accidental execution of code.
2. Different behavior for different contexts: It allows for different code execution based on the context (running as the main program or as a module). For example, you could have certain functions that are only executed when the script is run directly, or you could perform initialization or setup routines only when the script is run as the main program.
3. Protection against specifying arguments: When importing a script as a module, it's possible that the imported script might have its own command-line argument parsing code. The if __name__ == "__main__": guard prevents the imported script from unexpectedly running with the importing script's command-line arguments.

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