Inheriting and Extending .NET Types

Learn about inheriting exceptions in .NET to create custom exception types and extend existing types using static and extension methods for added functionality.

We'll cover the following

Inheriting exceptions
- Try it yourself
Extending types when we can’t inherit
Using static methods to reuse functionality
- Try it yourself
Using extension methods to reuse functionality
- Try it yourself

.NET has pre-built class libraries containing hundreds of thousands of types. Rather than creating our own completely new types, we can often get a head start by deriving from one of Microsoft’s types to inherit some or all of its behavior and then overriding or extending it.

Inheriting exceptions

As an example of inheritance, we will derive a new type of exception:

Step 1: In the PacktLibrary project, add a new class file named PersonException.cs.

Step 2: Modify the contents of the file to define a class named PersonException with three constructors, as shown in the following code:

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Introduction

Hello, C#! Welcome, .NET!

Speaking C#

Controlling Flow, Converting Types, and Handling Exception

Writing, Debugging, and Testing Functions

Building Your Own Types with Object-Oriented Programming

Implementing Interfaces and Inheriting Classes

Packaging and Distributing .NET Types

Working with Common .NET Types

Working with Files, Streams, and Serialization

Working with Data Using Entity Framework Core

Querying and Manipulating Data Using LINQ

Introducing Web Development Using ASP.NET Core

Building Websites Using ASP.NET Core Razor Pages

Building Websites Using the Model-View-Controller Pattern

Building and Consuming Web Services

Building User Interfaces Using Blazor

Conclusion

Inheriting and Extending .NET Types

Inheriting exceptions