Clean Code with C#: Refactor your legacy C# code base and improve application performance using best practices. 2 Ed

Clean Code with C#....2

Contributors....7

About the author....7

About the reviewers....8

Preface....34

Who this book is for....35

What this book covers....36

To get the most out of this book....40

Download the example code files....42

Conventions used....42

Get in touch....43

Share Your Thoughts....44

Download a free PDF copy of this book....45

Chapter 1: Coding Standards and Principles in C#....47

Technical requirements....49

Good code versus bad code....49

The need for coding standards, principles, and methodologies....52

Coding standards....54

Coding principles....55

Coding methodologies....68

Summary....94

Questions....96

Further reading....96

Chapter 2: Code Review – Process and Importance....100

A brief introduction to GitHub....102

What is GitHub?....103

GitHub’s use within the code review process....104

Resources for learning....107

The code review process....109

Preparing code for review....110

Leading a code review....114

Issuing a pull request....116

Responding to a pull request....123

Effects of feedback on reviewees....127

Knowing what to review....131

The company’s coding guidelines and business requirement(s)....132

Naming conventions....133

Formatting....133

Testing....134

Documentation....137

Architectural guidelines and design patterns....138

Performance and security....140

Knowing when to send code for review....141

Providing and responding to review feedback....143

Providing feedback as a reviewer....144

Responding to feedback as a reviewee....145

Summary....146

Questions....148

Further reading....148

Chapter 3: Classes, Objects, and Data Structures....150

Technical requirements....151

Organizing classes....152

A class should have only one responsibility....158

Class organization....161

Commenting for documentation generation....164

Cohesion and coupling....171

Tight coupling....173

Low coupling....175

Low cohesion....178

High cohesion....180

Designing for change....182

Interface-oriented programming....183

Dependency injection and inversion of control....188

The Law of Demeter....201

A good and a bad example (chaining) of the Law of Demeter....204

Immutable objects and data structures....207

Using records to create immutable objects....210

Objects should hide data and expose methods....212

An example of encapsulation....213

Data structures should expose data and have no methods....215

The SOLID software methodology....216

SRP....217

Open/closed principle (OCP)....218

Liskov substitution principle (LSP)....219

Interface segregation principle (ISP)....222

Dependency inversion principle (DIP)....223

Summary....225

Questions....226

Further reading....227

Chapter 4: Writing Clean Functions....229

Technical requirements....231

Understanding the difference between OOP and FP....231

Explanation of the differences....233

Understanding why FP can lead to cleaner functions....235

Unclean methods and how they affect software....238

FP and clean methods....242

FP examples....246

Keeping methods small....254

Indenting code....258

Breaking out of loops....259

Avoiding duplication....261

Avoiding multiple parameters....265

Implementing the SRP....268

Handling exceptions in FP....279

Adding comments for readability....284

XML documentation comments....284

Inline comments....285

Variable declaration and memory management....285

Declaring variables close to their usage....286

Disposing of resources....286

Applying security in methods, especially in APIs....287

Input validation....287

Authentication and authorization....288

Protecting sensitive data....288

Summary....289

Questions....290

Further reading....291

Chapter 5: Exception Handling....292

Technical requirements....293

Overview of exception handling in C#....294

try-catch....294

try-catch-finally....296

Clean code exception-handling principles....299

SRP....301

OCP....306

DIP....312

Best practices for handling exceptions....316

Handling the TPL AggregateException exception....319

Use await with try-catch inside async methods....320

Flatten the exception hierarchy....320

Handle individual exceptions....321

Handle exceptions as they occur....322

Creating custom exceptions and when to use them....323

Avoiding common mistakes in exception handling....325

Testing exception handling....330

Unit testing exception handling....331

Integration testing exception handling....333

End-to-end testing exception handling....338

An employee management example of mocking and unit testing with correct exception handling....339

Summary....348

Questions....349

Further reading....351

Chapter 6: Unit Testing....353

Technical requirements....353

Understanding unit testing....354

Writing testable code....354

TDD....355

An example of using the AAA TDD pattern....357

Choosing a testing framework....358

Testing framework attribute differences....360

TDD using MSTest....361

TDD using NUnit....362

TDD using xUnit....363

Running tests in Visual Studio....365

Writing effective unit tests....366

Using code coverage analysis in Visual Studio 2022....367

Ensuring your unit tests themselves are correct....367

Using stubs in place of mocks....368

Mocking data....369

Integrating tests into the continuous integration and deployment (CI/CD) pipeline....372

Integrating tests into an Azure DevOps CI/CD pipeline....372

Problem tests....374

Summary....375

Questions....376

Further reading....376

Chapter 7: Designing and Developing APIs....378

Technical requirements....379

What is an API?....379

APIs help different consumers build loosely coupled applications....381

Idempotent and non-idempotent operations....383

HTTP verbs....385

Important API design topics you must consider....388

How can clean code help API design and development?....393

The API design process....397

API security risks and their mitigations....402

On-premises APIs versus cloud APIs....407

API development in C#....411

Web API security with OWASP....416

Importance of OWASP adherence in C# API development....418

Creating an OWASP-compliant API....420

Implementing OWASP-compliant two-factor authentication (2FA)....424

OpenID Connect (OIDC) and OAuth 2.0 (OAuth2)....430

Summary....438

Questions....440

Further reading....441

Chapter 8: Addressing Cross-Cutting Concerns....444

A definition of cross-cutting concerns....445

Importance and impact on software development....450

Common examples of cross-cutting concerns....452

Logging....452

Error handling and exception management....455

Caching....464

Performance optimization....467

Transaction management....472

Validation....476

Auditing and compliance....479

Localization and internationalization....483

Logging and monitoring....488

Summary....490

Questions....492

Further reading....492

Chapter 9: AOP with PostSharp....495

Technical requirements....496

AOP....496

AOP frameworks....500

How AOP works with PostSharp....503

Extending the aspect framework....504

Project – Cross-cutting concerns reusable library....512

Adding a caching concern....514

Adding file logging capabilities....517

Adding an exception-handling concern....522

Adding a security concern....524

Adding a validation concern....531

Adding a transaction concern....541

Adding a resource pool concern....542

Adding a configuration settings concern....543

Adding an instrumentation concern....545

PostSharp and build pipeline considerations....547

Dynamic AOP with Castle.DynamicProxy....548

Summary....551

Questions....552

Further reading....552

Chapter 10: Using Tools to Improve Code Quality....554

Technical requirements....555

Code analysis....555

Using quick actions....558

Using the JetBrains dotTrace profiler....560

Using JetBrains ReSharper....565

Using Telerik JustDecompile....581

Continuous integration with GitHub Actions and CodeQL....584

Summary....585

Questions....587

Further reading....587

Chapter 11: Refactoring C# Code....589

Technical requirements....590

Application-level code smells....590

Boolean blindness....591

Combinatorial explosion....594

Contrived complexity....596

Data clump....599

Deodorant comments....600

Duplicate code....601

Lost intent....603

The mutation of variables....604

The oddball solution....609

Shotgun surgery....612

Solution sprawl....616

Uncontrolled side effects....616

Class-level code smells....618

Cyclomatic complexity....618

Divergent change....626

Downcasting....626

Excessive literal use....627

Feature envy....628

Inappropriate intimacy....631

Indecent exposure....631

The large class (the God object)....632

The lazy class (the freeloader and the lazy object)....633

The middleman class....634

The orphan class of variables and constants....634

Primitive obsession....636

Refused bequest....640

Speculative generality....641

Tell, Don’t Ask....641

Temporary fields....642

Method-level smells....642

The black sheep method....643

Cyclomatic complexity....643

Contrived complexity....643

Dead code....644

Excessive data return....644

Feature envy....645

Identifier size....645

Inappropriate intimacy....646

Long lines (God lines)....646

Lazy methods....647

Long methods (God methods)....647

Long parameter lists (too many parameters)....647

Message chains....648

The middleman method....648

Oddball solutions....648

Speculative generality....649

Summary....649

Questions....651

Further reading....653

Chapter 12: Functional Programming....654

Technical requirements....655

Imperative versus functional programming....655

Imperative programming....655

Key differences....660

Overview of functional programming in C#....663

First-class functions and Lambda expressions....666

Lambda expressions in C#....667

Higher-order functions....668

Immutability and pure functions....672

Functional composition....675

Using Lambda expressions....676

Using LINQ and extension methods....676

Using higher-order functions....677

Option types and the Maybe monad....678

Usage of option types in C#....681

The Maybe monad in C#....682

Functional error handling....684

Option types....687

The Maybe monad....687

The Either monad....687

Result objects....688

Functional data transformation and pipelines....689

Lazy evaluation....695

Pattern matching....698

Currying and partial application....702

Currying....702

Partial application....703

Key differences....703

Concurrency with functional programming....704

Recursion....712

Summary....715

Questions....717

Further reading....718

Chapter 13: Cross-Platform Application Development with MAUI....720

Technical requirements....721

Project overview....721

Windows version....722

Android version....724

Creating the project....732

Understanding XAML structure....738

The MVVM pattern....740

Adding CommunityToolkit.Mvvm....743

The models....745

The ViewModels....750

The views....757

Configuring our to-do application....764

Summary....765

Questions....767

Further reading....768

Chapter 14: Microservices....769

What are microservices?....771

The downsides of microservices, some gotchas experienced by microservices, and how they can be overcome and avoided....774

Comparison between microservices and monoliths....779

The design process for building successful microservices....783

The application life cycle management (ALM) of microservices....787

Microservice architecture patterns....792

Service registration and discovery....796

Service discovery....796

Service registration....799

Containerization and orchestration of microservices....800

Containerization....800

Orchestration....802

Serverless....804

API gateways....806

Event-driven communication....809

Service resilience and fault tolerance....812

Service monitoring and observability....816

Service monitoring....816

Observability....817

Security....819

CI/CD....822

Microservice testing....826

Scaling microservices....830

Versioning and compatibility....833

Microservices best practices and anti-patterns....837

Microservices best practices....837

Microservices anti-patterns....838

Case studies and real-world examples....842

Summary....845

Questions....847

Further reading....848

Assessments....850

Chapter 1....851

Chapter 2....853

Chapter 3....854

Chapter 4....856

Chapter 5....858

Chapter 6....860

Chapter 7....862

Chapter 8....864

Chapter 9....865

Chapter 10....866

Chapter 11....868

Chapter 12....875

Chapter 13....877

Chapter 14....881

Index....883

Why subscribe?....951

Other Books You May Enjoy....952

Packt is searching for authors like you....955

Share Your Thoughts....956

Download a free PDF copy of this book....956

Traditionally associated with developing Windows desktop applications and games, C# is now used in a wide variety of domains, such as web and cloud apps, and has become increasingly popular for mobile development. Despite its extensive coding features, professionals experience problems related to efficiency, scalability, and maintainability because of bad code. Clean Code in C# will help you identify these problems and solve them using coding best practices.

The book starts with a comparison of good and bad code, helping you understand the importance of coding standards, principles, and methodologies. You'll then get to grips with code reviews and their role in improving your code while ensuring that you adhere to industry-recognized coding standards. This C# book covers unit testing, delves into test-driven development, and addresses cross-cutting concerns. You'll explore good programming practices for objects, data structures, exception handling, and other aspects of writing C# computer programs. Once you've studied API design and discovered tools for improving code quality, you'll look at examples of bad code and understand which coding practices you should avoid.

By the end of this clean code book, you'll have the developed skills you need in order to apply industry-approved coding practices to write clean, readable, extendable, and maintainable C# code.

What you will learn

• Write code that allows software to be modified and adapted over time
• Implement the fail-pass-refactor methodology using a sample C# console application
• Address cross-cutting concerns with the help of software design patterns
• Write custom C# exceptions that provide meaningful information
• Identify poor quality C# code that needs to be refactored
• Secure APIs with API keys and protect data using Azure Key Vault
• Improve your code's performance by using tools for profiling and refactoring

Who this book is for

This coding book is for C# developers, team leads, senior software engineers, and software architects who want to improve the efficiency of their legacy systems. A strong understanding of C# programming is required.