Clean Code 

Complexity keeps rising 

Code = Communication 

Code = Communication “Any fool can write code that a computer can understand. 
 Good programmers write code that humans can understand.” —Refactoring, Martin Fowler with Kent Beck, 1996 

Speed & Quality 

SDO Performance Organizational performance Industry (control) Enterprise (control) CULTURE OF PSYCHOLOGICAL SAFETY Burnout Construct Control variable Second-order construct Common goal for team or organization Predictive relationship Mixed results Negative predictive relationship Continuous delivery Loosely coupled architecture Monitoring Deployment automation HEAVYWEIGHT CHANGE PROCESS CODE MAINTAINABILITY Trunk-based development CLEAR CHANGE PROCESS Continuous integration Automated testing Cloud - DISASTER RECOVERY TESTING - - - Availability Software delivery performance 

SDO Performance Burnout Continuous delivery Loosely coupled architecture Monitoring Deployment automation CODE MAINTAINABILITY Trunk-based development Continuous integration Automated testing Cloud DISASTER RECOVERY TESTING - - Availability Software delivery performance 

Clean Code is the basis for Secure Code 

10x more time reading “Indeed, the ratio of time spent reading versus writing is well over 10 to 1. We are constantly reading old code as part of the effort to write new code. ... [Therefore,] making it easy to read makes it easier to write.” ― Robert C. Martin, Clean Code: A Handbook of Agile Software Craftsmanship 

10x more time reading 

Optimize? 10x more time reading 

@nicokrijnen nkrijnen nicokrijnen Nico Krijnen 

Value of software 

Value of software Flexible 

Value of software Works Can change 

Value of software Works Can change = 

Value of software Works Can change = 

Value of software Works Can change = 

Value of software Works Can change = 

Code that is easy to change 

Code that is easy to change • Easy to read and understand intention 

Code that is easy to change • Easy to read and understand intention • Version control 

Code that is easy to change • Easy to read and understand intention • Version control • Automated tests 

Code that is easy to change • Easy to read and understand intention • Version control • Automated tests Safety net } 

Clean Code? 

Clean Code • Polite • Self-explaining Robert C. Martin – Uncle Bob 

Clean Code • Polite • Self-explaining • Code without surprises Robert C. Martin – Uncle Bob Daniel Terhorst-North 

Clean Code • Polite • Self-explaining • Code without surprises 

Clean Code • Naming • Structure 

Clean Code • Naming • Structure • TDD Kent Beck 

Clean Code • Naming • Structure • TDD • Refactoring Kent Beck Martin Fowler 

Victor Rentea Kent Beck 

SOLID • Single-responsibility principle • Open–closed principle • Liskov substitution principle • Interface segregation principle • Dependency inversion principle Robert C. Martin – Uncle Bob 

CUPID – for joyful coding • Composable • Unix philosophy • Predictable • Idiomatic • Domain-based https://dannorth.net/2022/02/10/cupid-for-joyful-coding/ Daniel Terhorst-North 

CUPID – Composable Plays well with others • Small surface area • Intention-revealing • Minimal dependencies Daniel Terhorst-North 

CUPID – Unix philosophy Does one thing well • A simple, consistent model • Single purpose vs. single responsibility Daniel Terhorst-North 

CUPID – Predictable Does what you expect • Behaves as expected • Deterministic • Observable Daniel Terhorst-North 

CUPID – Idiomatic Feels natural • Language idioms • Local idioms Daniel Terhorst-North 

CUPID – Domain-based The solution domain models the problem domain 
 in language and structure • Domain-based language • Domain-based structure • Domain-based boundaries Daniel Terhorst-North 

CUPID – for joyful coding • Composable • Unix philosophy • Predictable • Idiomatic • Domain-based https://dannorth.net/2022/02/10/cupid-for-joyful-coding/ Daniel Terhorst-North 

Code is not done until it: 1. ... 2. ... 3. ... 4. ... 

Absolutely gorgeous Code is not done until it: 1. Works 2. Communicates 3. No duplicates 4. Fewest methods and classes Fred George Kent Beck 

Code That Fits in Your Head No more than 7 (±2) Mark Seemann 

Test Driven Development • TDD helps code design • Intention = captured and re-enforced by tests • Tests make code safer and easier to change Kent Beck 

Domain-Driven Design Keep systems as simple as possible 
 to solve real problems for your domain. Eric Evans 

What if you have no tests? "There is only one way to eat an elephant: a bite at a time." understandlegacycode.com “Legacy Code is code without tests” Michael Feathers: Working Effectively with Legacy Code 

Clean Code! 

void printOwing() { printBanner(); // Print details. System.out.println("name: " + name); System.out.println("amount: " + getOutstanding()); } void printOwing() { printBanner(); printDetails(getOutstanding()); } void printDetails(double outstanding) { System.out.println("name: " + name); System.out.println("amount: " + outstanding); } vs 

var d; // elapsed time in days var elapsedTimeInDays; var daysSinceCreation; var daysSinceModification; vs 

vs if (age >= 18) { ... } else { ... } boolean isOldEnoughToBuyAlcohol = age >= 18; if (isOldEnoughToBuyAlcohol) { ... } else { ... } if (isOldEnoughToBuyAlcohol(age)) { ... } else { ... } public boolean isOldEnoughToBuyAlcohol(int age) { return age >= 18; } vs 

public boolean checkPasswordStrength(String password) { boolean isNotBlank = password != null && !password.isBlank(); if (isNotBlank) { boolean hasSpecialChar = password.chars().anyMatch(Character::isLetterOrDigit); if (hasSpecialChar) { boolean longEnough = password.length() >= 10; if (longEnough) { return true; } else { throw new IllegalArgumentException("Must be at least 10 characters"); } } else { throw new IllegalArgumentException("Must contain at least one special character"); } } else { throw new IllegalArgumentException("Password must not be blank"); } } public void checkPasswordStrength(String password) { if (password == null || password.isBlank()) throw new IllegalArgumentException("Password must not be blank"); if (password.chars().noneMatch(Character::isLetterOrDigit)) throw new IllegalArgumentException("Must contain at least one special character"); if (password.length() < 10) throw new IllegalArgumentException("Must be at least 10 characters"); } vs 

public void checkPasswordStrength(String password) { checkNotBlank(password); checkHasSpecialCharacter(password); checkHasMinimumLength(password); } private void checkNotBlank(String password) { if (password == null || password.isBlank()) throw new IllegalArgumentException("Password must not be blank"); } private void checkHasSpecialCharacter(String password) { if (password.chars().noneMatch(Character::isLetterOrDigit)) throw new IllegalArgumentException("Must contain at least one special character"); } private void checkHasMinimumLength(String password) { if (password.length() < 10) throw new IllegalArgumentException("Must be at least 10 characters"); } public void checkPasswordStrength(String password) { if (password == null || password.isBlank()) throw new IllegalArgumentException("Password must not be blank"); if (password.chars().noneMatch(Character::isLetterOrDigit)) { throw new IllegalArgumentException("Must contain at least one special character"); } if (password.length() < 10) { throw new IllegalArgumentException("Must be at least 10 characters"); } } vs 

class Password { private final String password; public Password(String password) { this.password = password; checkNotBlank(); checkHasSpecialCharacter(); checkHasMinimumLength(); } private void checkNotBlank() { if (password == null || password.isBlank()) throw new IllegalArgumentException("Password must not be blank"); } private void checkHasSpecialCharacter() { if (password.chars().noneMatch(Character::isLetterOrDigit)) throw new IllegalArgumentException("Must contain at least one special character"); } private void checkHasMinimumLength() { if (password.length() < 10) throw new IllegalArgumentException("Must be at least 10 characters"); } ... } 

2000 classes 25 lines per class 1 to 3 lines per method <2 cyclomatic complexity vs 100 classes 500 lines per class 5 - 80+ cyclomatic complexity 

Why is not all code clean? 

Business / Time pressure? • The need to go fast is real! • 'Slower but steady' requires discipline. 

Lack of support? • How do you build understanding from business stakeholders • Hard to explain the need for refactoring. [don't] • Easy to explain the need for quality. [do] • You will fall when you run too fast. You may make the finish, but you won't be able to run the next race. 

# developers doubles every 5 years At any point in time, 
 50% of developers 
 have less than 5 years experience 

The path to Clean Code 

Convince your organization 

Convince your business # of Tests 

Convince your business 16 Accelerate: State of DevOps 2019 | How Do We C SOFTWARE DEVELOPMENT SOFTWARE DEPLOYMENT SERVICE OPERAT Lead Time Change Fail Availability Deployment Frequency Time to Restore FOUR KEY METRICS The first four metrics that capture the effectiveness of the development and delivery process can be summarized in terms of throughput and stability. We measure the throughput of the so ware delivery process using lead time of code changes from check-in to release along with deployment fr Stability is measured using time to r the time it takes from detecting a us impacting incident to having it rem and change fail rate, a measure of t of the release process. PERFORMANCE METRICS # of Tests 

Master the fundamentals Learn Framework / Library Use Learn Cloud landscape Use Learn Clean code Use Learn Use Switch programming language Switch programming language 

It's a journey 

Learn & Practice = Experience • TDD / BDD • Refactoring • Absolutely gorgeous • Version control • DDD 

Helpful tooling • IDE / IntelliJ (hints + safe refactoring) • SonarLint / SonarQube • ArchUnit • Checkstyle • PMD, FindBugs, SpotBugs 

Helpful tooling • IDE / IntelliJ (hints + safe refactoring) • SonarLint / SonarQube • ArchUnit • Checkstyle • PMD, FindBugs, SpotBugs 😀 🙅 

Expand your vocabulary • Design patterns • Heuristics • Algorithms • Pair programming 

Learning angles • Read books, watch talks • Follow training • Form group, do katas • Practice on side projects https://tinyurl.com/luminis-clean-code 

Clean Code is written over time • First focus on making it work • Spend time to make it communicate • Your understanding of a codebase will grow • Any time you see or touch code, make it fit your latest insights 

Clean as-you-code • Refactor in your task cycle • Boy/girl scout rule 
 "Always leave the campground cleaner than you found it." • Code rub 

Take away 

Take away Any codebase can become clean 

Take away Any codebase can become clean Yours too! 

Take away Any codebase can become clean Yours too! https://tinyurl.com/luminis-clean-code @nicokrijnen nkrijnen nicokrijnen