The DRY meaning “Don’t repeat yourself” principle is a best practice in software development that recommends software engineers to do something once, and only once. The concept, which is often credited to Andrew Hunt and David Thomas, authors of “The Pragmatic Programmer”, is the tongue-in-cheek opposite of the WET principle, which stands for “write everything twice”.

According to the DRY principle, every discrete chunk of knowledge should have one, unambiguous, authoritative within a system. The goal of the DRY principles is to lower technical best by eliminating redundancies in process and logic whenever possible.

Redundancies in logic

To prevent redundancies in logic (code), followers of the DRY principle use abstraction to minimize repetition. Abstraction is the process of removing characteristics until only the most essential characteristics remain.

Redundancies in process

To prevent redundancies in processes (actions required to achieve a result), followers of the DRY principle seek to ensure that there is only one way to complete a particular process. Automating the steps wherever possible also reduces redundancy, as well as the number of actions required to complete a task.

An important goal of the DRY principle is to improve the maintainability of code during all phases of its lifecycle. When the DRY principle is followed, for example, a software developer should be able to change code in one place and have the change automatically applied to every instance of the code in question.

As programmers, we collect, organize, maintain, and harness knowledge. We document knowledge in specifications, we make it come alive in running code, and we use it to provide the checks needed during testing.

Violations of DRY

“We enjoy typing” (or, “Wasting everyone’s time”.): “We enjoy typing”, means writing the same code or logic again and again. It will be difficult to manage the code and if the logic changes, then we have to make changes in all the places where we have written the code, thereby wasting everyone’s time.

How to Avoid DRY

To avoid violating the DRY principle, divide your system into pieces. Divide your code and logic into smaller reusable units and use that code by calling it where you want. Don’t write lengthy methods, but divide logic and try to use the existing piece in your method.

DRY Benefits

Less code is good: It saves time and effort, is easy to maintain, and also reduces the chances of bugs. One good example of the DRY principle is the helper class in enterprise libraries, in which every piece of code is unique in the libraries and helper classes. I chose this topic because as a programmer, it is always important to know why design principles are useful for us, what and how to implement them in our programming.

Software Design Principles DRY and KISS – DZone Java

The DRY Principle: Benefits and Costs with Examples (thevaluable.dev)

What is DRY principle? – Definition from WhatIs.com (techtarget.com)

From the blog CS@Worcester – Software Intellect by rkitenge91 and used with permission of the author. All other rights reserved by the author.