1 2 :mod:`__main__` --- Top-level script environment 3 ================================================ 4 5 .. module:: __main__ 6 :synopsis: The environment where the top-level script is run. 7 8 -------------- 9 10 ``'__main__'`` is the name of the scope in which top-level code executes. 11 A module's __name__ is set equal to ``'__main__'`` when read from 12 standard input, a script, or from an interactive prompt. 13 14 A module can discover whether or not it is running in the main scope by 15 checking its own ``__name__``, which allows a common idiom for conditionally 16 executing code in a module when it is run as a script or with ``python 17 -m`` but not when it is imported:: 18 19 if __name__ == "__main__": 20 # execute only if run as a script 21 main() 22 23 For a package, the same effect can be achieved by including a 24 ``__main__.py`` module, the contents of which will be executed when the 25 module is run with ``-m``. 26
