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Design patterns

By definition, a design pattern is a set of proven de facto industry standards and best practices for resolving recurring problems. Design patterns are not ready-made solutions. Rather, they're a way or template to implement and apply the best possible solution for your problem.

It's equally true that if a design pattern is not implemented in the right way, it creates a lot of problems rather than solving the one you expected to solve. So it's very important to know which design pattern, if any, is right for a specific scenario.

Design patterns are a common paradigm to describe the problem and how to solve it. It's usually not language specific. Design patterns can protect you from the design problems that generally occur in the later stages of development.

There are numerous advantages to using design patterns, as follows:

Improves software reusability
Development cycle becomes faster
Makes the code more readable and maintainable
Increases the efficiency and enhances the overall software development
Provides common vocabulary to describe problems and best possible solutions in a more abstract way

And you can count many more. In the following sections, we will gain a deep understanding of how to make your code modular, loosely coupled, independent, testable, and maintainable, by following certain principles and patterns.

This chapter will cover in-depth ideas about the Dependency Inversion Principle (DIP), the Inversion of Control paradigm, and DI design pattern.

Most developers use the terms design principle and design pattern interchangeably, even though there is a difference between them.

Design principle: Generically, this is a guideline about what is the right way and what is the wrong way to design your application. Design principles always talk about what to do instead of how to do it.

Design patterns: A generic and reusable solution for commonly occurring problems. Design patterns talk about how to solve the problems in a given software design context by providing clear methodologies.

The first step towards making your code cleaner, readable, decoupled, maintainable, and modular is to learn the design principle called DIP.