Code Quality and Design

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I welcome any feedback or suggestions for improving this guide. Please feel free to reach out with your thoughts or questions.

• Email: dgerman.codequality@gmail.com

Introduction

This document is a practical guide to help with software development mentoring and code review. It is a selected collection of principles, patterns, and examples I have gathered over the years. It's not meant to be a complete textbook that covers everything.

Most of the ideas and material presented here are not my own, but are drawn from books and articles I have read (sources are mentioned throughout). I do not claim original credit for these concepts; this guide is a collection of insights gathered from a wide range of respected sources.

Table of Contents

• Code Quality Design

  • Motivation for Good Design

  • Code Review Checklist

  • Object Oriented Programming

    • Pillars of OOP

      • Pillars of OOP Encapsulation Abstraction

        • Minimize Accessibility of Classes and Members

      • Inheritance

      • Polymorphism

      • Composition

      • Abstract Classes vs Interfaces

    • Core Design Principles

      • DRY Principle

      • ETC Principle

      • Program to an interface; not an Implementation (GOF 18)

      • Find What Is Varying and Encapsulate It (Shalloway 123)

      • SOLID Design Principles

        • Single Responsibility Principle (SRP)

        • Open Closed Principle (OCP)

        • Liskov Substitution Principle (LSP)

          • Avoiding Liskov Substitution Principal Violations in Type Hierarchies

        • Interface Segregation Principle (ISP)

        • Dependency Inversion Principle (DIP)

      • Prefer Composition over Class Inheritance

        • Inheritance vs Composition Analogy

    • Design Patterns

      • The Facade Pattern with the Single Responsibility Principle

      • Decorator Pattern

      • Strategy Pattern Implementation for JSON Processing

      • Template Method

    • Dependencies and Coupling

      • Stable vs Volatile Dependencies

      • The Dependency Rule

      • Using the new keyword

      • Design Relationships

      • Relationship between Dependency Inversion, Dependency Injection, Inversion of Control, and SOLID

    • Implementation Techniques and Heuristics

      • Memory Allocation and Management Reference Types Value Types Arrays and Linked Lists

      • Evolving Configuration Interfaces From Boolean Flags to Expressive Design

      • Static Methods

      • Self Validating Value Objects in C

      • Some Object Oriented Design Heuristics Riel updated

  • Functional Programming

    • Imperative vs Functional Declarative Expressive Style of Programming

    • Functional in the Small and Object Oriented in the Large

    • Prefer Dictionary over Switch Statement

    • Using SelectMany

    • Introduction to Result T

    • Higher Order Function Examples

    • Transitioning from Classes to Records and Adopting IImmutableList in C

    • Function composition and method chaining

    • Defensive Copying in C Example

    • Partial Application Example

  • Concurrency

    • Understanding Threads in Programming A Restaurant Analogy

    • Understanding the Thread Pool in NET

  • Performance

    • Utilizing Record Structs for Enhanced Performance in NET

    • Maximizing Performance and Readability with const Variables in C

    • Exploring Performance with New Collection Expression Syntax in C 12

  • Language Specifics (C#/.NET)

    • Using Required Members in C 11

    • var keyword

    • When to use Target typed new expressions

    • Difference between const and static readonly

  • Anti-Patterns and Code Smells

    • Ambient Context

    • Naming Examples

    • Big Ball of Mud

    • Using Exceptions for Control Flow

    • High Complexity

    • Explicit case analysis switch if else statement

  • Game Development

    • Unity Case Study – Refactoring “Tanks” with SOLID Principles and Design Patterns

    • Dependency Inversion Principle in Unity (DIP)

  • Testing

    • Finding Test Cases

    • Code Coverage

    • How do we write a test for a private method

    • Seam Interface

    • Comparing Objects for Equality in C Using JSON Serialization

  • Python

    • Immutable DTOs in Python

  • Glossary

    • Cognitive Complexity

    • Cohesion

    • Composition Root

    • Coupling

    • Cyclomatic Complexity

    • DTO Data Transfer Object

    • Dependency Injection DI

    • Interception

    • Inversion of Control IoC

    • Modularity Module

    • POCO Plain Old CLR Objects

  • Appendices

    • OOP Design Quotes

    • References