Chapter Summary

In this chapter, we studied metaclasses and explored examples of them in action. Metaclasses allow us to tap into the class creation protocol of Python, in order to manage or augment user-defined classes. Because they automate this process, they can provide better solutions for API writers then manual code or helper functions; because they encapsulate such code, they can minimize maintenance costs better than some other approaches.

Along the way, we also saw how the roles of class decorators and metaclasses often intersect: because both run at the conclusion of a class statement, they can sometimes be used interchangeably. Class decorators can be used to manage both class and instance objects; metaclasses can, too, although they are more directly targeted toward classes.

广告：个人专属 VPN，独立 IP，无限流量，多机房切换，还可以屏蔽广告和恶意软件，每月最低仅 5 美元

Since this chapter covered an advanced topic, we’ll work through just a few quiz questions to review the basics (if you’ve made it this far in a chapter on metaclasses, you probably already deserve extra credit!). Because this is the last part of the book, we’ll forego the end-of-part exercises. Be sure to see the appendixes that follow for pointers on installation steps, and the solutions to the prior parts’ exercises.

Once you finish the quiz, you’ve officially reached the end of this book. Now that you know Python inside and out, your next step, should you choose to take it, is to explore the libraries, techniques, and tools available in the application domains in which you work. Because Python is so widely used, you’ll find ample resources for using it in almost any application you can think of—from GUIs, the Web, and databases to numeric programming, robotics, and system administration.

This is where Python starts to become truly fun, but this is also where this book’s story ends, and others’ begin. For pointers on where to turn after this book, see the list of recommended follow-up texts in the Preface. Good luck with your journey. And of course, “Always look on the bright side of Life!”