In this chapter, we saw how to use asynchronous I/O in Python using asyncio. For many scenarios, the asyncio module is still a bit raw and unfinished, but there should not be any obstacles in using it. Creating a fully functional server/client setup is still a tad complicated, but the most obvious use of asyncio is the handling of basic network I/O such as database connections and external resources such as websites. Especially, the latter takes only a few lines to implement with the use of asyncio, removing some very important bottlenecks from your code.
The point of this chapter is understanding how to tell Python to wait for results in the background instead of simply waiting or polling for them as usual. In Chapter 13, Multiprocessing – When a Single CPU Core Is Not Enough you will learn about multiprocessing, which is also an option for handling stalling resources. However, the goal of multiprocessing is actually to use multiple processors instead of handling stalling resources. When it comes to potentially slow external resources, I recommend that you always use asyncio, if at all possible.
When building utilities based on the asyncio library, make sure you search for premade libraries to solve your problems, as many of them are currently being developed. While writing this chapter, Python 3.5 was not officially out yet, so the odds are that a lot more documentation and libraries using the async/await syntax will pop up soon. To make sure you do not repeat work that others have done, search the Internet thoroughly before writing your own code extending on asyncio.
The next chapter will explain a completely different topic—the construction of classes using metaclasses. Regular classes are created using the type class, but now we will see how we can extend and modify the default behavior to make a class do pretty much anything we want. Metaclasses even make it possible to have automatically registering plugins and add features to classes in a very magical way—in short, how to customize not just the class instances but the class definitions themselves.