The Reasons to Avoid Enumerations

Alternatives to Enumerations

Converting Enumeration to a Class

The Reasons to Never Stringify Data

Reaping the Benefits of String Encapsulation

Avoiding Primitive Types Altogether

Example - Modeling Money

Persistence - Small-scale CQRS and DDD

Demonstrating Persistence

Summary

Understanding the Role of Null

Why Compilers Still Rely on Null

Using Callback on Optional Content

Overloading Existing APIs to Never Return Null

Returning an Optional Object

Implementing Custom Option Type

Consuming the Option

Persistence - Creating Complex Domain Objects

Summary

Course Overview

What’s Wrong with Status Codes

Understanding Effects of Throwing Exceptions

What Exceptions Are Not Meant to Do

Leave Nothing Exceptional in Exceptions

Returning a Polymorphic Type Instead of an Excep

Separating Positive and Negative Return Values

Inventing the Either Type

Consuming the Either Type

Summary

Version Check

What Follows in This Course

Traditional Defensive Techniques

Defensive Design - An Experiment

Called Method Cannot Defend

Defining Function Domains

Summary

Creating Objects

Creating Consistent Objects

Pros and Cons of Multiple Constructors

Understanding Limitations of the Constructor

Promoting Constructor into Builder

Variations in the Builder Implementation

Summary

Reaping the Benefits of Constructor Validation

Defending in Property Setters

Understanding Distinct Kinds of Properties

Defending in Complex Mutations

Function Domains Revisited

When Constructor Depends on Multiple Objects

Creating Objects in Small Steps

Persistence and Parameterized Constructors

Summary

Introducing Guard Clauses

Guarding Against Null Only

Dont Guard Business Rules

Removing Guards Through Design

Turning Domain Rules into Rule Objects

Turning Rule Objects into Active Elements

Completing the Students Filter

Persistence - Querying View Models

Summary

Encapsulating State

Keeping Related Data Together

Turning Chained Ifs into the Chain of Rules

Making Friends with Regular Expressions

Replacing Branching with Regular Expressions

Moving Expressions out to Configuration

Persistence - Creating and Updating Domain Objects

Summary

Reconsidering Immutable Objects

Turning Classes Immutable

Avoiding Aliasing Bugs Altogether

The Downside of Immutability

Constrained Mutability with Set-once Properties

Consuming Semi-mutable Objects

Using Historical Model

Implementing Simple Historical Model

Summary