Test Your Knowledge: Answers

How did you do? Here are the answers I came up with, though there may be multiple solutions to some quiz questions. Again, even if you’re sure you got a question right, I encourage you to look at these answers for additional context. See the chapter’s text for more details if any of these responses don’t make sense to you.

 

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  1. Software quality, developer productivity, program portability, support libraries, component integration, and simple enjoyment. Of these, the quality and productivity themes seem to be the main reasons that people choose to use Python.
  2. Google, Industrial Light & Magic, EVE Online, Jet Propulsion Labs, Maya, ESRI, and many more. Almost every organization doing software development uses Python in some fashion, whether for long-term strategic product development or for short-term tactical tasks such as testing and system administration.
  3. Python’s downside is performance: it won’t run as quickly as fully compiled languages like C and C++. On the other hand, it’s quick enough for most applications, and typical Python code runs at close to C speed anyhow because it invokes linked-in C code in the interpreter. If speed is critical, compiled extensions are available for number-crunching parts of an application.
  4. You can use Python for nearly anything you can do with a computer, from website development and gaming to robotics and spacecraft control.
  5. import this triggers an Easter egg inside Python that displays some of the design philosophies underlying the language. You’ll learn how to run this statement in the next chapter.
  6. “Spam” is a reference from a famous Monty Python skit in which people trying to order food in a cafeteria are drowned out by a chorus of Vikings singing about spam. Oh, and it’s also a common variable name in Python scripts....
  7. Blue. No, yellow!

Python Is Engineering, Not Art

When Python first emerged on the software scene in the early 1990s, it spawned what is now something of a classic conflict between its proponents and those of another popular scripting language, Perl. Personally, I think the debate is tired and unwarranted today—developers are smart enough to draw their own conclusions. Still, this is one of the most common topics I’m asked about on the training road, so it seems fitting to say a few words about it here.

The short story is this: you can do everything in Python that you can in Perl, but you can read your code after you do it. That’s it—their domains largely overlap, but Python is more focused on producing readable code. For many, the enhanced readability of Python translates to better code reusability and maintainability, making Python a better choice for programs that will not be written once and thrown away. Perl code is easy to write, but difficult to read. Given that most software has a lifespan much longer than its initial creation, many see Python as a more effective tool.

The somewhat longer story reflects the backgrounds of the designers of the two languages and underscores some of the main reasons people choose to use Python. Python’s creator is a mathematician by training; as such, he produced a language with a high degree of uniformity—its syntax and toolset are remarkably coherent. Moreover, like math, Python’s design is orthogonal—most of the language follows from a small set of core concepts. For instance, once one grasps Python’s flavor of polymorphism, the rest is largely just details.

By contrast, the creator of the Perl language is a linguist, and its design reflects this heritage. There are many ways to accomplish the same tasks in Perl, and language constructs interact in context-sensitive and sometimes quite subtle ways—much like natural language. As the well-known Perl motto states, “There’s more than one way to do it.” Given this design, both the Perl language and its user community have historically encouraged freedom of expression when writing code. One person’s Perl code can be radically different from another’s. In fact, writing unique, tricky code is often a source of pride among Perl users.

But as anyone who has done any substantial code maintenance should be able to attest, freedom of expression is great for art, but lousy for engineering. In engineering, we need a minimal feature set and predictability. In engineering, freedom of expression can lead to maintenance nightmares. As more than one Perl user has confided to me, the result of too much freedom is often code that is much easier to rewrite from scratch than to modify.

Consider this: when people create a painting or a sculpture, they do so for themselves for purely aesthetic purposes. The possibility of someone else having to change that painting or sculpture later does not enter into it. This is a critical difference between art and engineering. When people write software, they are not writing it for themselves. In fact, they are not even writing primarily for the computer. Rather, good programmers know that code is written for the next human being who has to read it in order to maintain or reuse it. If that person cannot understand the code, it’s all but useless in a realistic development scenario.

This is where many people find that Python most clearly differentiates itself from scripting languages like Perl. Because Python’s syntax model almost forces users to write readable code, Python programs lend themselves more directly to the full software development cycle. And because Python emphasizes ideas such as limited interactions, code uniformity and regularity, and feature consistency, it more directly fosters code that can be used long after it is first written.

In the long run, Python’s focus on code quality in itself boosts programmer productivity, as well as programmer satisfaction. Python programmers can be creative, too, of course, and as we’ll see, the language does offer multiple solutions for some tasks. At its core, though, Python encourages good engineering in ways that other scripting languages often do not.

At least, that’s the common consensus among many people who have adopted Python. You should always judge such claims for yourself, of course, by learning what Python has to offer. To help you get started, let’s move on to the next chapter.