Thursday, February 16, 2012 DRY (Don't Repeat Yourself) programming
I'm capturing this here for my own reference, but it may be useful to others.
In software engineering, Don't Repeat Yourself (DRY) is a principle of software development aimed at reducing repetition of information of all kinds, especially useful in multi-tier architectures. The DRY principle is stated as "Every piece of knowledge must have a single, unambiguous, authoritative representation within a system." The principle has been formulated by Andy Hunt and Dave Thomas in their book The Pragmatic Programmer. They apply it quite broadly to include "database schemas, test plans, the build system, even documentation." When the DRY principle is applied successfully, a modification of any single element of a system does not require a change in other logically-unrelated elements. Additionally, elements that are logically related all change predictably and uniformly, and are thus kept in sync. Besides using methods and subroutines in their code, Thomas and Hunt rely on code generators, automatic build systems, and scripting languages to observe the DRY principle across layers.
- Orthogonality and the DRY Principle
- Don't Repeat Yourself at WikiWikiWeb
- Once and Only Once at WikiWikiWeb
- 97 Things Every Programmer Should Know (O'Reilly)
- Codereflect.com - DRY Principle
Thursday, February 16, 2012 John Whish
My version of this is broadly speaking "if you find yourself doing copy / paste, then should think twice" :)