4 Key Principles to Craft High-Quality Code Thiago Bomfim

Table of contents The Dependency Inversion Principle The Single Responsibility Principle Don’t Repeat Yourself Keep It Simple, Stupid 01 02 04 03 SRP DRY DIP KISS

SRP The Single Responsibility Principle 01

— Robert C. Martin “Gather together those things that change for the same reason, and separate those things that change for different reasons. ”

The Single Responsibility Principle How can you apply SRP? ● Keep your classes and methods small. ● Be careful with many dependencies, look at your imports.

The Single Responsibility Principle How can you identify if you are not applying the SRP? ● If you need to change many files to include or change a behavior. ● If you need to change the same file for more than one reason.

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DRY Don’t Repeat Yourself 02

— Robert C. Martin - Clean Code “This is one of the most important rules in this book, and you should take it very seriously. ”

Don’t Repeat Yourself How can you apply DRY? ● Avoid duplication. ● Any time you see duplication in the code, it could probably become a subroutine or maybe another class outright.

Don’t Repeat Yourself How can you identify if you are not applying the DRY? ● If you are doing Ctrl+C/Ctrl+V and nothing changes. ● If you need to resolve the same problem twice in different places.

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DIP The Dependency Inversion Principle 03

— Robert C. Martin “Depend in the direction of abstraction. High level modules should not depend upon low level details. ”

The Dependency Inversion Principle How can you apply DIP? ● Use abstraction to separate the layers. ● Don’t depend on the implementation, depend on the abstractions.

The Dependency Inversion Principle How can you identify if you are not applying the DIP? ● If you need to change your core application, or your domain because some API you consume changes, you are probably violating the DRY. ● Can you change the API you consume to another vendor? If you can’t, maybe you are violation the DRY.

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KISS Keep It Simple, Stupid 04

— Leonardo da Vinci “Simplicity is the ultimate sophistication. ”

— Antoine de Saint-Exupery “Perfection is achieved not when there is nothing more to add, but when there is nothing left to take away. ”

Keep It Simple, Stupid How can you apply KISS? ● Avoid complex architectures and design solutions to solve simple problems. ● Simplicity should be a key design goal, and complicated complexity should be avoided.

Keep It Simple, Stupid How can you identify if you are not applying the KISS? ● How easy is your solution to be understood and extended? ● Are you doing premature optimization?

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REFERENCES Keep Learning 05

Clean Code A Handbook of Agile Software Craftsmanship - Robert Cecil Martin.

The Pragmatic Programmer - Andy Hunt, Dave Thomas

Test-Driven Java Development - Viktor Farcic, Alex Garcia

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