Why Ruby is Simple

下面这段话原文摘录自《The Ruby Way》一书，大意是“为什么说Ruby是一种简单的语言”。摘录它的原因有二：（1）myan刚才走到我旁边说：“我感觉Ruby还是一个相当复杂的语言，它的语法并不像C那么简练。”（2）这段话引用了大量的名人名言，算得上技术传播的一个好范本。

So one of Ruby's virtues is simplicity. Shall I quote other thinkers on the subject? According to Antoine de St. Exupéry, "Perfection is achieved, not when there is nothing left to add, but when there is nothing left to take away."

But Ruby is a complex language. How can I say that it is simple?

If we understood the universe better, we might find a "law of conservation of complexity"a fact of reality that disturbs our lives like entropy so that we cannot avoid it but can only redistribute it.

And that is the key. We can't avoid complexity, but we can push it around. We can bury it out of sight. This is the old "black box" principle at work; a black box performs a very complex task, but it possesses simplicity on the outside.

If you haven't already lost patience with my quotations, a word from Albert Einstein is appropriate here: "Everything should be as simple as possible, but no simpler."

So, in Ruby we see simplicity embodied from the programmer's view (if not from the view of those maintaining the interpreter). Yet we also see the capacity for compromise. In the real world, we must bend a little. For example, every entity in a Ruby program should be a true object, but certain values such as integers are stored as immediate values. In a tradeoff familiar to computer science students for decades, we have traded elegance of design for practicality of implementation. In effect, we have traded one kind of simplicity for another.

What Larry Wall said about Perl holds true: "When you say something in a small language, it comes out big. When you say something in a big language, it comes out small." The same is true for English. The reason that biologist Ernst Haeckel could say "Ontogeny recapitulates phylogeny" in only three words was that he had these powerful words with highly specific meanings at his disposal. We allow inner complexity of the language because it enables us to shift the complexity away from the individual utterance.

I would state this guideline this way: Don't write 200 lines of code when 10 will do.

I'm taking it for granted that brevity is generally a good thing. A short program fragment will take up less space in the programmer's brain; it will be easier to grasp as a single entity. As a happy side effect, fewer bugs will be injected while the code is written.

Of course, we must remember Einstein's warning about simplicity. If we put it too high on our list of priorities, we will end up with code that is hopelessly obfuscated. Information theory teaches us that compressed data is statistically similar to random noise; if you have looked at C or APL or regular expression notationespecially badly writtenyou have experienced this truth firsthand. Simple, but not too simple; that is the key. Embrace brevity, but do not sacrifice readability.