Choosing Variable Names

It often surprises me that developers seem to choose completely useless variable names like MyVariable when creating an application. Although MyVariable could be an interesting variable name for an example in a book, it never has a place in any sort of production code. Even then, I try to create book examples with meaningful variable names, especially when getting past the initial “Hello World” example. Variable names are important because they tell others:

 

  • What sort of information the variable stores
  • When the variable is commonly used
  • Where the variable is used
  • How to use the variable correctly
  • Why the variable is important


In some cases, the variable name could even indicate who created the variable; although, this sort of information is extremely rare. If you never thought a variable name should contain all that information, then perhaps you haven’t been choosing the best variable names for your application.

Even with these restrictions in place, choosing a variable name can be uncommonly hard if you want to maximize the name’s value to both yourself and other developers. Some organizations make the selection process easier by following certain conventions. For example, a form of Hungarian Notation, where certain type prefixes, suffixes, and other naming conventions are used, is a common way to reduce the complexity of creating a variable name. In fact, Hungarian Notation (or some form of it) is often used to name objects, methods, functions, classes, and other programming elements as well. For example, NamArCustomers could be an array of customer names (Nam for names, Ar for array). The use of these two prefixes would make it instantly apparent when the variable is being used incorrectly, such as assigning a list of numbers to the array. The point is that an organizational variable naming policy can reduce complexity, make the names easy to read for anyone, and reduces the time the developer spends choosing a name.

 

Before I get a ton of e-mail on the topic, yes, I know that many people view Hungarian notation as the worst possible way to name variables. They point out that it only really works with statically typed languages and that it doesn’t work at all for languages such as JavaScript. All that I’m really pointing out is that some sort of naming convention is helpful—whether you use something specific like Hungarian Notation is up to you.


Any variable name you create should convey the meaning of that variable to anyone. If you aren’t using some sort of pattern or policy to name the variables, then create a convention that helps you create the names in a consistent manner and document it. When you create a variable name, you need to consider these kinds of questions:

 

  1. What information does the variable contain (such as a list of names)?
  2. How is the variable used (such as locally or globally, or to contain coordinates, or a special kind of object)?
  3. When appropriate, what kind of information does the variable contain (such as a string or the coordinate of a pixel on screen)?
  4. Is the variable used for a special task (such as data conversion)?
  5. What case should prefixes, suffixes, and other naming elements appear in when a language is case sensitive?

The point is that you need to choose variable names with care so that you know what they mean later. Carefully chosen variable names make it possible for you to read your code with greater ease and locate bugs a lot faster. They also make it easier for others to understand your code and for you to remember what the code does months after you’ve written it. However, most important of all, useful variable names help you see immediately that a variable is being using the wrong way, such as assigning the length of a name string to a coordinate position on screen (even though both variables are integer values). Let me know your thoughts about variable naming at John@JohnMuellerBooks.com.

 

Author: John

John Mueller is a freelance author and technical editor. He has writing in his blood, having produced 99 books and over 600 articles to date. The topics range from networking to artificial intelligence and from database management to heads-down programming. Some of his current books include a Web security book, discussions of how to manage big data using data science, a Windows command -line reference, and a book that shows how to build your own custom PC. His technical editing skills have helped over more than 67 authors refine the content of their manuscripts. John has provided technical editing services to both Data Based Advisor and Coast Compute magazines. He has also contributed articles to magazines such as Software Quality Connection, DevSource, InformIT, SQL Server Professional, Visual C++ Developer, Hard Core Visual Basic, asp.netPRO, Software Test and Performance, and Visual Basic Developer. Be sure to read John’s blog at http://blog.johnmuellerbooks.com/.

When John isn’t working at the computer, you can find him outside in the garden, cutting wood, or generally enjoying nature. John also likes making wine and knitting. When not occupied with anything else, he makes glycerin soap and candles, which comes in handy for gift baskets. You can reach John on the Internet at John@JohnMuellerBooks.com. John is also setting up a website at http://www.johnmuellerbooks.com/. Feel free to take a look and make suggestions on how he can improve it.