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SOLID practices

In today's lesson, we're gonna discuss the SOLID principles in detail, where each letter refers to one good practice in software development. Our explanations will contain brilliant illustrations from Deric Bailey (CC-SA 3.0 license) and, of course, practical examples. This article is more advanced and assumes the knowledge of at least Basic Good Practices for Software Design. In addition to SOLID, there's also a series of bad practices that we should avoid, STUPID. You can find the link to it at the end of the article.


SOLID, an acronym, sums up the most important best practices. If you follow them, your applications will have a potential of the quality software. Derick Bailey created a perfect series of illustrations for the SOLID practices to help you remember them. We'll explain the principles in detail, let's say what the acronym means first:

  • Single Responsibility Principle
  • Open/closed Principle
  • Liskov Substitution Principle
  • Interface Segregation Principle
  • Dependency Inversion Principle
SOLID – Software development is not a Jenga game

Image: Mark Nijhof, Twitter

"Software development is not a Jenga game." If you don't know Jenga, it's a game about building a tower of blocks as high as possible until it falls down. Software development mustn't be only about functionality, but also about maintaining the architecture, the support system, preventing the application from falling apart.

SOLID - Single responsibility principle

SOLID – Single Responsibility Principle

Image: Derick Bailey, CC-SA 3.0


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Article description

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Practical examples on the SOLID best practices, the SRP, Open/closed, Liskov substitution, Interface segregation and Dependency Inversion principles.

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Article has been written for you by David Capka Hartinger
The author is a programmer, who likes web technologies and being the lead/chief article writer at He shares his knowledge with the community and is always looking to improve. He believes that anyone can do what they set their mind to.
Unicorn university David learned IT at the Unicorn University - a prestigious college providing education on IT and economics.