CSC/ECE 517 Fall 2009/wiki3 4 br

Topic: DRY principle for data Most of the literature on the DRY principle relates to code. But the principle also applies to data. Survey the issues related to copying the same data, and give reasons (e.g., caching) why it might sometimes be desirable, and how one should decide where it is helpful not to follow this general rule.

An overview of the concepts

DRY (or Don't Repeat Yourself) is a software engineering principle that says that "every piece of knowledge must have a single, unambiguous, authoritative representation within a system" [1]. By applying DRY practice to your software, the system is broken down with logically unrelated pieces separated, allowing easier changes to one element without affecting the system. Also, by not having the same code, or even the same functionality, in two different locations, only a change in one area of the system is required to enhancement or fix a bug.

Don't Repeat Yourself

File:DRY.jpg

DRY principle - related to code

• Example: DRY

 class Person
   attr_accessor :name
 end

References

1. http://en.wikipedia.org/wiki/DRY

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