CSC/ECE 517 Fall 2009/wiki3 4 ashi4

DRY Principle for Data

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Introduction

Donot Repeat Yourself (DRY) also known as Duplication Is Evil (DIE) is one of the most fundamental principles of programming, or rather we can say that it is the most important principle of good programming. This principle was formulated by Andrew Hunt and David Thomas in their book The Pragmatic Programmer. The principle states that "Every piece of knowledge must have a single, unambiguous, authoritative representation within a system.". This principle has been broadly accepted and acknowledged by the developers across the globe. It is considered to be one of the best coding practices to build an efficient and flexible code which is not only easy to understand but easy to maintain too. A parallel concept to DRY is Orthogonality which is making the components of the system as functionally independent as possible. It is well understood and an accepted fact that the DRY and the Orthogonality principle together lead to a very well structured code as discussed here. But if we observe the DRY principle more carefully, it is easy to notice that DRY is not only applicable to code but it is applicable to any piece of knowledge that can be represented in some way; one such form of knowledge representation is data. In fact, data and knowledge are used more or less interchangeably. The purpose of this document is to emphasize on the fact that the DRY principle is not only applicable to the code but to the data as well.

References

1. Andrew Hunt and David Thomas, "Pragmatic Programmer : From Journeyman to Master", Addison-Weasley Publications, October-99.