This appendix describes the new Windows launcher for Python, installed with Python 3.3 automatically, and available separately on the Web for use with older versions. Though the new launcher comes with some pitfalls, it provides some much-needed coherence for program execution when multiple Pythons coexist on the same computer.

I’ve written this page for programmers using Python on Windows. Though it is platform-specific by nature, it’s targeted at both Python beginners (most of whom get started on this platform), as well as Python developers who write code to work portably between Windows and Unix. As we will see, the new launcher changes the rules on Windows radically enough to impact everyone who uses Python on Windows, or may in the future.