16
Tue, Jul
4 New Articles

RPG Academy: Write Better Code — Choosing Appropriate Names for Variables, Procedures, and Functions

RPG
Typography
  • Smaller Small Medium Big Bigger
  • Default Helvetica Segoe Georgia Times

While the previous two TechTips focused on the prefixes for different types of variables, this one is about the name itself. Here I explain why using simple names is of paramount importance to writing better code.

Choosing appropriate names for variables is as critical as correctly using the prefixes. Check out the previous two TechTips for a quick refresh on prefixes. For instance, W_DF is not very informative, but W_DeliveryFee or W_Delivery_Fee is. Choosing appropriate, meaningful names for variables makes your code more efficient in the sense that you’ll waste less time understanding and maintaining it later.

Other than the words themselves, you need to use some sort of separation between them to increase readability. “Modern” languages typically use something called “camel case.” The idea behind this funny name is that you capitalize the first letter of every word contained in the variable name, like W_DeliveryFee, thus creating a camel-like “hump” in the middle of the word’s “back.”

Another option is using the underscore character (_) to separate the words. This can create longer variable names, but it simplifies complicated names such as P_usdtoeur, which becomes P_USD_to_Eur. I usually use the underscore to separate the words, but as I said, this can lead to very long variable names. When the name gets too long, I switch to camel case.

Speaking of long names, did you know that the maximum length allowed by RPG for a variable is 4,096 characters? While it doesn’t make any sense whatsoever to even consider using such a long name, always keep in mind that you need to find the right balance between readability and maintainability: W_I_use_this_variable_to_store_the_value_converted_to_integer is way too long, while W_Converted_to_Int is equally informative but much more maintainable. However, this raises a question: You probably noticed that I abbreviated “integer” to “int”; should you abbreviate words in variable names?

The answer is “sometimes.” When the abbreviation is a common one, such as “Qty” for “Quantity” or “Amt” for “Amount,” you should, in my opinion, abbreviate it. Don’t abbreviate other words, though, or you’ll jeopardize your recently earned readability. For example, consider a variable that will hold a consistency check. It’s okay to abbreviate “check” as “chk” because that’s a fairly well-known abbreviation. However, don’t even consider abbreviating “consistency,” or you’ll risk confusing it with some other word starting with “C” later, when you (or another programmer) reads the code in a couple of months. So, a work variable related to a consistency check could be named W_Consistency_Chk, but not W_Cnstcy_Chk.

Naming Procedures and Functions

I’ve already mentioned the golden rule of function naming a couple of times in previous TechTips of this series, but it’s worth mentioning again: Function names should always start with a verb (which can be abbreviated or not, like a variable name) followed by the object over which the action (or the verb) is going to be performed. They should also be descriptive enough for a programmer to understand what the function does, in broad terms, without having to look at the function’s code. For instance, Retrieve_Item_Qty is the name of a function that retrieves the quantity of a given item; Itmqty, or anything similar, is just rubbish!

If your functions are built in such a way that they perform only one task, choosing an adequate name shouldn’t be a problem. In fact, if you look at any given function and find it hard to name, consider reviewing the function and splitting it into several smaller functions. If your function performs several tasks, then it shouldn’t be just one function. A good example of this is the Rtv_DayOfWeek function from earlier in the series, which can be split into two. In case you don’t remember, the original function performed two tasks; it calculated the day of the week, producing a numeric value that corresponded to each day (1 for Monday, 2 for Tuesday, and so on), and then it translated that numeric value into a human-readable value (Monday, Tuesday, etc.). So you can assign each of the tasks to a new function and name it appropriately: Clc_DayOfWeek and Rtv_DayOfWeek, respectively.

Naturally, there are always exceptions to this rule. Functions also encapsulate complex functionality, providing the programmer with a “black box” or API that he or she can use without caring how the function does what it does, and allowing the programmer to focus on the result that it makes available instead. This is the type of situation in which documentation helps a lot.

 

Some gurus advocate that you should prefix the function name (the verb+subject I mentioned earlier) with the name of the module. For instance, if the Clc_DayOfWeek and Rtv_DayOfWeek functions were included in a generic module named Dates, their names would be Dates_Clc_DayOfWeek and Dates_Rtv_DayOfWeek, respectively. While I don’t disagree with this naming convention, it has advantages and disadvantages. A big, yet manageable disadvantage is that the procedure names get longer, which can lead to some annoying misspellings. The main advantage is eliminating the risk of duplicated procedure names in two (or more) different service programs, which could cause a compilation error further down the road if you try to compile a program that uses both of those service programs.

The next TechTip will continue to discuss naming conventions, focusing on physical and logical file names. Until then, feel free to share your knowledge and experience with the rest of the readers in the comments section below. It’s always nice to hear from you!

Rafael Victoria-Pereira

Rafael Victória-Pereira has more than 20 years of IBM i experience as a programmer, analyst, and manager. Over that period, he has been an active voice in the IBM i community, encouraging and helping programmers transition to ILE and free-format RPG. Rafael has written more than 100 technical articles about topics ranging from interfaces (the topic for his first book, Flexible Input, Dazzling Output with IBM i) to modern RPG and SQL in his popular RPG Academy and SQL 101 series on mcpressonline.com and in his books Evolve Your RPG Coding and SQL for IBM i: A Database Modernization Guide. Rafael writes in an easy-to-read, practical style that is highly popular with his audience of IBM technology professionals.

Rafael is the Deputy IT Director - Infrastructures and Services at the Luis Simões Group in Portugal. His areas of expertise include programming in the IBM i native languages (RPG, CL, and DB2 SQL) and in "modern" programming languages, such as Java, C#, and Python, as well as project management and consultancy.


MC Press books written by Rafael Victória-Pereira available now on the MC Press Bookstore.

Evolve Your RPG Coding: Move from OPM to ILE...and Beyond Evolve Your RPG Coding: Move from OPM to ILE...and Beyond
Transition to modern RPG programming with this step-by-step guide through ILE and free-format RPG, SQL, and modernization techniques.
List Price $79.95

Now On Sale

Flexible Input, Dazzling Output with IBM i Flexible Input, Dazzling Output with IBM i
Uncover easier, more flexible ways to get data into your system, plus some methods for exporting and presenting the vital business data it contains.
List Price $79.95

Now On Sale

SQL for IBM i: A Database Modernization Guide SQL for IBM i: A Database Modernization Guide
Learn how to use SQL’s capabilities to modernize and enhance your IBM i database.
List Price $79.95

Now On Sale

BLOG COMMENTS POWERED BY DISQUS

LATEST COMMENTS

Support MC Press Online

$

Book Reviews

Resource Center

  • SB Profound WC 5536 Have you been wondering about Node.js? Our free Node.js Webinar Series takes you from total beginner to creating a fully-functional IBM i Node.js business application. You can find Part 1 here. In Part 2 of our free Node.js Webinar Series, Brian May teaches you the different tooling options available for writing code, debugging, and using Git for version control. Brian will briefly discuss the different tools available, and demonstrate his preferred setup for Node development on IBM i or any platform. Attend this webinar to learn:

  • SB Profound WP 5539More than ever, there is a demand for IT to deliver innovation. Your IBM i has been an essential part of your business operations for years. However, your organization may struggle to maintain the current system and implement new projects. The thousands of customers we've worked with and surveyed state that expectations regarding the digital footprint and vision of the company are not aligned with the current IT environment.

  • SB HelpSystems ROBOT Generic IBM announced the E1080 servers using the latest Power10 processor in September 2021. The most powerful processor from IBM to date, Power10 is designed to handle the demands of doing business in today’s high-tech atmosphere, including running cloud applications, supporting big data, and managing AI workloads. But what does Power10 mean for your data center? In this recorded webinar, IBMers Dan Sundt and Dylan Boday join IBM Power Champion Tom Huntington for a discussion on why Power10 technology is the right strategic investment if you run IBM i, AIX, or Linux. In this action-packed hour, Tom will share trends from the IBM i and AIX user communities while Dan and Dylan dive into the tech specs for key hardware, including:

  • Magic MarkTRY the one package that solves all your document design and printing challenges on all your platforms. Produce bar code labels, electronic forms, ad hoc reports, and RFID tags – without programming! MarkMagic is the only document design and print solution that combines report writing, WYSIWYG label and forms design, and conditional printing in one integrated product. Make sure your data survives when catastrophe hits. Request your trial now!  Request Now.

  • SB HelpSystems ROBOT GenericForms of ransomware has been around for over 30 years, and with more and more organizations suffering attacks each year, it continues to endure. What has made ransomware such a durable threat and what is the best way to combat it? In order to prevent ransomware, organizations must first understand how it works.

  • SB HelpSystems ROBOT GenericIT security is a top priority for businesses around the world, but most IBM i pros don’t know where to begin—and most cybersecurity experts don’t know IBM i. In this session, Robin Tatam explores the business impact of lax IBM i security, the top vulnerabilities putting IBM i at risk, and the steps you can take to protect your organization. If you’re looking to avoid unexpected downtime or corrupted data, you don’t want to miss this session.

  • SB HelpSystems ROBOT GenericCan you trust all of your users all of the time? A typical end user receives 16 malicious emails each month, but only 17 percent of these phishing campaigns are reported to IT. Once an attack is underway, most organizations won’t discover the breach until six months later. A staggering amount of damage can occur in that time. Despite these risks, 93 percent of organizations are leaving their IBM i systems vulnerable to cybercrime. In this on-demand webinar, IBM i security experts Robin Tatam and Sandi Moore will reveal:

  • FORTRA Disaster protection is vital to every business. Yet, it often consists of patched together procedures that are prone to error. From automatic backups to data encryption to media management, Robot automates the routine (yet often complex) tasks of iSeries backup and recovery, saving you time and money and making the process safer and more reliable. Automate your backups with the Robot Backup and Recovery Solution. Key features include:

  • FORTRAManaging messages on your IBM i can be more than a full-time job if you have to do it manually. Messages need a response and resources must be monitored—often over multiple systems and across platforms. How can you be sure you won’t miss important system events? Automate your message center with the Robot Message Management Solution. Key features include:

  • FORTRAThe thought of printing, distributing, and storing iSeries reports manually may reduce you to tears. Paper and labor costs associated with report generation can spiral out of control. Mountains of paper threaten to swamp your files. Robot automates report bursting, distribution, bundling, and archiving, and offers secure, selective online report viewing. Manage your reports with the Robot Report Management Solution. Key features include:

  • FORTRAFor over 30 years, Robot has been a leader in systems management for IBM i. With batch job creation and scheduling at its core, the Robot Job Scheduling Solution reduces the opportunity for human error and helps you maintain service levels, automating even the biggest, most complex runbooks. Manage your job schedule with the Robot Job Scheduling Solution. Key features include:

  • LANSA Business users want new applications now. Market and regulatory pressures require faster application updates and delivery into production. Your IBM i developers may be approaching retirement, and you see no sure way to fill their positions with experienced developers. In addition, you may be caught between maintaining your existing applications and the uncertainty of moving to something new.

  • LANSAWhen it comes to creating your business applications, there are hundreds of coding platforms and programming languages to choose from. These options range from very complex traditional programming languages to Low-Code platforms where sometimes no traditional coding experience is needed. Download our whitepaper, The Power of Writing Code in a Low-Code Solution, and:

  • LANSASupply Chain is becoming increasingly complex and unpredictable. From raw materials for manufacturing to food supply chains, the journey from source to production to delivery to consumers is marred with inefficiencies, manual processes, shortages, recalls, counterfeits, and scandals. In this webinar, we discuss how:

  • The MC Resource Centers bring you the widest selection of white papers, trial software, and on-demand webcasts for you to choose from. >> Review the list of White Papers, Trial Software or On-Demand Webcast at the MC Press Resource Center. >> Add the items to yru Cart and complet he checkout process and submit

  • Profound Logic Have you been wondering about Node.js? Our free Node.js Webinar Series takes you from total beginner to creating a fully-functional IBM i Node.js business application.

  • SB Profound WC 5536Join us for this hour-long webcast that will explore:

  • Fortra IT managers hoping to find new IBM i talent are discovering that the pool of experienced RPG programmers and operators or administrators with intimate knowledge of the operating system and the applications that run on it is small. This begs the question: How will you manage the platform that supports such a big part of your business? This guide offers strategies and software suggestions to help you plan IT staffing and resources and smooth the transition after your AS/400 talent retires. Read on to learn: