It means that you should put new code in new classes/modules. Existing code should be modified only for bug fixing. New classes can reuse existing code via inheritance. Open/closed principle is intended to mitigate risk when introducing new functionality. Since you don’t modify existing code you can be assured that it wouldn’t be broken. It … Read more
Bob Martin has tried to clear this up on multiple occasions. The problem is that there are two different principles in play here; and it’s extremely unfortunate that one of them doesn’t really have a name, which is why it’s commonly conflated with the SRP. Functions should do one thing. They should do it well. … Read more
The books Agile Software Development, Principles, Patterns, and Practices and Agile Principles, Patterns, and Practices in C# are the best resources for fully understanding the original goals and motivations behind the Dependency Inversion Principle. The article “The Dependency Inversion Principle” is also a good resource, but due to the fact that it is a condensed … Read more
What is an example of the Liskov Substitution Principle?