When we discussed the Object-Oriented Programming principles in Chapter 2, Diving into OOP Principles we introduced association, aggregation, composition, encapsulation, inheritance, and polymorphism. These principles are the foundations of any language that can be defined as object oriented. Therefore, they are the basic principles without which we can not say that we are applying the OOP model.
However, the simple principles of OOP are not enough to guarantee us the creation of robust and easily maintainable applications. They simply provide us with tools that allow us to model a problem using abstractions we call objects. The robustness, maintainability, and flexibility of an application mainly depends on how we design it, decide to put together its components, and use the principles of OOP.
According to Robert C. Martin, one of the co-authors of the Agile Manifesto, there are three characteristics of bad design to be avoided:
Rigidity: This is the difficulty of...