Import or Execute Pattern in Python

The concern is documenting an idiom to be used when it is desirable to run a python file immediately if called from the shell, but import the function when called from the Python REPL. I call this Import or Execute Pattern.

1. import or execute pattern: name & main

• in python, there are specially named bindings __name__ and __main__ allowing us to detect whether a module is
• run as a script from a shell
• imported into another module from the REPL
• when you add print(__name__) at the end of the module, the module name is printed during the first import
• if (and only if) the function with print(__name__) in the module is called from the shell with python script.py the shell return

▶ python script.py
__main__

• you can modify the behavior so that the module is
• executed from a shell
• loaded from the REPL

2. syntax

• add the following at the end of the script and if you call if from the shell and not from the REPL, the script executes immediately

if __name__ == "__main__":
    FUNCTION_TO_BE_EXECUTED()