| |
| :mod:`__main__` --- Top-level script environment |
| ================================================ |
| |
| .. module:: __main__ |
| :synopsis: The environment where the top-level script is run. |
| |
| ``'__main__'`` is the name of the scope in which top-level code executes. |
| A module's __name__ is set equal to ``'__main__'`` when read from |
| standard input, a script, or from an interactive prompt. |
| |
| A module can discover whether or not it is running in the main scope by |
| checking its own ``__name__``, which allows a common idiom for conditionally |
| executing code in a module when it is run as a script or with ``python |
| -m`` but not when it is imported: |
| |
| if __name__ == "__main__": |
| # execute only if run as a script |
| main() |
| |
| For a package, the same effect can be achieved by including a |
| ``__main__.py`` module, the contents of which will be executed when the |
| module is run with ``-m``. |