Python 3 文档(简体中文) 3.2.2 documentation

Version: 3.2.2
27.3. builtins — Built-in objects << 27.4. __main__ — Top-level script environment (Source) >>27.5. warnings — Warning control

27.4. __main__ — Top-level script environment

This module represents the (otherwise anonymous) scope in which the interpreter’s main program executes — commands read either from standard input, from a script file, or from an interactive prompt. It is this environment in which the idiomatic “conditional script” stanza causes a script to run:

if __name__ == "__main__":