Understanding the SOLID Principles

On this entry we will discuss about the book section “Understanding the SOLID Principles” by Edward Guiness from the book “Ace the Programming Interview: 160 Questions and Answers for Success” published by Wiley in 2013. This chapter talks about principles for object-oriented programming and design. This will make your code clearer, minimize dependencies and practical.

The first is Single Responsibility Principle which mean that your class don’t have to be mixed with many responsibilities, it is preferred to divide it in different classes, one per task. The second, the Open/Closed Principle, states that a class should be open for extension but closed for modification.  According to the lecture you don’t have to modify your class, you only need to create a new class that inherits from base class and add the new function that you need.

Liskov Substitution Principle said that you should be free to substitute a child class in a function that expects to deal with the base class. The it is the principle of Interface Segregation Principle which says that instead of creating a big interface with many functions split it in a collection of smaller interfaces. So, classes can then pick and choose what they implement rather than having to use all or nothing.

The last one is Dependency Inversion Principle a principle that offers you to write code that refers to interfaces or perhaps abstract classes, instead of writing code that refers to actual classes.

Provided that, SOLID principles are guides that can be applied in the development of software to eliminate code that is not correct, causing the source code to be reprogrammed until it is readable and extensible. This serves to minimize the dependency between the interfaces, that means that less dependent code, and more code easy to understand, without having to compromise functionality.