What is a design pattern? – Introduction

Since you just purchased a book about design patterns, I guess you have some idea of what design patterns are, but let’s make sure that we are on the same page.Abstract definition: A design pattern is a proven technique that we can use to solve a specific problem.In this book, we apply different patterns to solve various problems and leverage some open-source tools to go further, faster! Abstract definitions make people sound smart, but understanding concepts requires more practice, and there is no better way to learn than by experimenting with something, and design patterns are no different.If that definition does not make sense to you yet, don’t worry. You should have enough information by the end of the book to correlate the multiple practical examples and explanations with that definition, making it crystal clear.I like to compare programming to playing with LEGO® because what you have to do is very similar: put small pieces together to create something bigger. Therefore, if you lack imagination or skills, possibly because you are too young, your castle might not look as good as someone with more experience. With that analogy in mind, a design pattern is a plan to assemble a solution that fits one or more scenarios, like the tower of a castle. Once you designed a single tower, you can build multiple by following the same steps. Design patterns act as that tower plan and give you the tools to assemble reliable pieces to improve your masterpiece (program).However, instead of snapping LEGO® blocks together, you nest code blocks and interweave objects in a virtual environment!Before going into more detail, well-thought-out applications of design patterns should improve your application designs. That is true whether designing a small component or a whole system. However, be careful: throwing patterns into the mix just to use them can lead to the opposite result: over-engineering. Instead, aim to write the least amount of readable code that solves your issue or automates your process.As we have briefly mentioned, design patterns apply to different software engineering levels, and in this book, we start small and grow to a cloud-scale! We follow a smooth learning curve, starting with simpler patterns and code samples that bend good practices to focus on the patterns—finally ending with more advanced topics and good practices.Of course, some subjects are overviews more than deep dives, like automated testing, because no one can fit it all in a single book. Nonetheless, I’ve done my best to give you as much information about architecture-related subjects as possible to ensure the proper foundations are in place for you to get as much as possible out of the more advanced topics, and I sincerely hope you’ll find this book a helpful and enjoyable read.Let’s start with the opposite of design patterns because it is essential to identify wrong ways of doing things to avoid making those mistakes or to correct them when you see them. Of course, knowing the right way to overcome specific problems using design patterns is also crucial.