1.4 Characteristics of Great Code

What do we mean by great code ? Different programmers will have different definitions for great code, so it is impossible to provide an all-encompassing definition that will satisfy everyone. However, there are certain attributes of great code that nearly everyone will agree upon, and we'll use some of these common characteristics to form our definition. For our purposes, here are some attributes of great code:

Uses the CPU efficiently (which means the code is fast)
Uses memory efficiently (which means the code is small)
Uses system resources efficiently
Is easy to read and maintain
Follows a consistent set of style guidelines
Uses an explicit design that follows established software engineering conventions
Is easy to enhance
Is well- tested and robust (meaning that it works)
Is well-documented

We could easily add dozens of items to this list. Some programmers, for example, may feel that great code must be portable, that it must follow a given set of programming style guidelines, or that it must be written in a certain language (or that it must not be written in a certain language). Some may feel that great code must be written as simply as possible, while others may feel that great code is written quickly. Still others may feel that great code is created on time and under budget. You can probably think of additional characteristics.

So what is great code? Here is a reasonable definition:

Great code is software that is written using a consistent and prioritized set of good software characteristics. In particular, great code follows a set of rules that guide the decisions a programmer makes when implementing an algorithm as source code.

Two different programs do not have to follow the same set of rules (that is, they need not possess the same set of characteristics) in order for both to be great programs. As long as they each consistently obey their particular set of rules, they can both be examples of great code. In one environment, a great program may be one that is portable across different CPUs and operating systems. In a different environment, efficiency (speed) may be the primary goal, and portability may not be an issue. Both could be shining examples of great code, even though their goals might be mutually exclusive. Clearly, neither program would be an example of great code when examined according to the rules of the other program; but as long as the software consistently follows the guidelines established for that particular program, you can argue that it is an example of great code.